No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effect of Hardness on the Surface Integrity of AISI 4340 Steel
Abstract
The effect of hardness on the residual stress in the machined surface of AISI 4340 steel was studied. Chips produced during the machining also were examined and the surface structure was investigated using optical microscope and scanning transmission microscope. Reflection electron diffraction study revealed the existence of austenite in the white layer of the machined surface together with untempered martensite. The residual stress near the machined surface or hardened steel is a compressive stress, and it changes to tensile stress as the hardness decreases. Chip segmentation was observed when steel with hardness of over Rc 50 was machined.
... Large tool edge radius results in increasing compressive residual stresses in the hoop and axial directions compared with small edge radius. Furthermore, they found that increasing the hardness of the workpiece material shifted surface residual stresses from tension to compression; the same results were reported in Ref. [122]. Zhang et al. [81] experimentally investigated the effects of the cutting parameters, namely, cutting speed, depth of cut, and feedrate, on induced subsurface residual stresses based on Taguchi method during finish hard turning. ...
... Several analytical based models for determining residual stresses in machining operations have been proposed since the early pioneering work of Liu and Barash [136,137], which introduced an idealized qualitative method with a small line element subjected to elastic-plastic loading and unloading process for understanding the residual stresses generation mechanism. Matsumoto et al. [122,138] used A comprehensive review on residual stresses in turning the analytical method for rolling contact firstly introduced by Merwin and Johnson [139] to investigate the effects of workpiece hardness on the induced residual stresses in orthogonal machining of AISI 4340 steel. Using the same method as reported in Ref. [139], Jacobus et al. [72] employed a plane-strain thermoelastic-plastic model for predicting the biaxial residual stresses profiles in orthogonal turning. ...
... Many researchers reported that increasing the hardness of the workpiece material shifted surface residual stresses from tension to compression as well as results in a deeper compressive residual stresses zone with higher peak compressive residual stresses [121,122,184,206] . This can be explained as follows: when turning higher hardness workpiece, the induced tensile stresses which resulting in tensile plastic deformation behind cutting tool is larger than that in cutting less hard material. ...
Residual stresses induced during turning processes can affect the quality and performance of machined products, depending on its direction and magnitude. Residual stresses can be highly detrimental as they can lead to creeping, fatigue, and stress corrosion cracking. The final state of residual stresses in a workpiece depends on its material as well as the cutting-tool configuration such as tool geometry/coating, cooling and wear conditions, and process parameters including the cutting speed, depth-of-cut and feed-rate. However, there have been disagreements in some literatures regarding influences of the above-mentioned factors on residual stresses due to different cutting conditions, tool parameters and workpiece materials used in the specific investigations. This review paper categorizes different methods in experimental, numerical and analytical approaches employed for determining induced residual stresses and their relationships with cutting conditions in a turning process. Discussion is presented for the effects of different cutting conditions and parameters on the final residual stresses state.
... American society of metal-machining studied the surface quality after different processes, and provided the empirical data of surface integrity. However, the fundamental relationship between turning mechanism and surface integrity was not clarified, and the research on surface integrity is mostly focused on mild steel [1]. No much research on hardened steel with a high hardness of greater than 65 HRC has been done, and the results of these researches are inconsistent. ...
... The concept of surface integrity was first proposed by Field et al in 1964, and the evaluation method of surface integrity was subsequently proposed in 1972 [3]. At present, as shown in figure.1, the research of surface integrity mainly focuses on surface topography, surface residual stress, microstructure and hardness, etc [1][2] [4]. Among these, the surface compressive residual stress is beneficial to the fatigue life of component, which is of great significance for anti-fatigue, because that the distribution of surface compressive residual stress is the key factor of contact anti-fatigue [5]. ...
... At present, the conventional finishing processes mainly include hard turning, high-speed milling and grinding, etc. The hard turning can induce a deeper compressive residual stress layer into the hardened steel GCr15 than that induced by the grinding, but the multiple crack sources on the circumferential surface increase, and thus the fatigue life of GCr15 decreases [1]. Therefore, the finishing process of key component is still mainly grinding. ...
As an important finish machining process, the grinding process plays an important role in the equipment manufacturing industry. This paper gives a quick overview of the development of surface integrity theory, illustrates the important influence of surface integrity on the fatigue life of component, introduces the development and research status of grinding process, and states the theory and application of grinding process with superior surface integrity after the case hardening or surface modification of key component.
... Okushimba and Kakino [5] states that the tensile residual stresses developed by heat generation/ temperature effects and compressive residual stresses by mechanical actions regarding machining operation which similar to Henriksen's conclusions. Matsumoto et al. [6] investigated the residual stresses in machining of AISI 4340 steel and revealed that asincreasing depth of cut and feed during machining operation, machined surface was distorted and it causes to increase in residual stresses.Navas et al. [7] revealed the effect of variable cutting tool geometry on surface stresses. These residual stresses measured by X-ray diffraction method for different cutting speed, feed rate and tool nose radius. ...
... The compressive residual stresses developed during shaping of workpiece and this compressive residual stresses increases fatigue life of component [4][5][6]. It assisted to develop quality characteristic of product, therefore larger the better chosen for S/N ratio and means. ...
... In case of increase in cutting speed reduces the main effect plot of signal to noise ratio and means. Therefore it found reduction in compressive residual stresses [6]. Hence 1 st level was optimizing for lower cutting speed of 220m/min. ...
... These are a martensitic phase transformation in the near-surface structure, yielding surface or near-surface elements due to thermal stresses caused by machining heat, and uneven plastic deformation of surface or subsurface elements. Under normal circumstances, when there is no excessive tool wear or abusive machining practice, very little martensitic formation is observed in the machined surface layer of hardened steel [25]. The existence of untempered martensite in the subsurface produces a compressive residual stress due to its larger volume. ...
... If the material is yielded in compression by the excessive cutting heat, then the surface element would be stressed in tension by the bulk material upon cooling and a tensile residual stress would result. On the other hand, the mechanical effect of cutting could produce either compressive residual stress or tensile residual stress [25,26]. It was found that the mechanical effect was the dominant factor producing residual stress in the machined surface. ...
... When the cutting direction is parallel to the specimen length, the residual compressive stress produced is higher than that produced by cutting in the direction perpendicular to the specimen length. The most likely cause of the difference in the residual stress is the difference in the cutting mechanism [25]. The sharp surface profile together with the shallow compressive residual stress of the ground specimen has brought a lower fatigue limit [11]. ...
... Several studies have investigated the capability of the process to compete with grinding, and most have concluded that at proper conditions with a good machine, hard turning can produce dimensional accuracy and surface finishes acceptable for most applications. Matsumoto et al. [1986] were able to hard turn parts with surface finish ranging from 0.045-0.197 µm, and surface waviness from 0.775-1.26 ...
... This was verified by Brinksmeier et al. [1982] and Konig et al. [1993]. As expected, the magnitude and depth of residual stresses are a function of tool geometry and process conditions [Matsumoto et al. 1986, Tonshoff et al. 1995, Brinksmeier et al. 1982 which was generated with a significantly worn tool. ...
The energy dissipated in hard machining operation is converted into heat which raises the temperature in the cutting zone. With the increase of cutting temperature; tool wear, surface roughness, dimensional inaccuracy increases significantly. Various researchers worked on various techniques to effectively control the increased cutting temperature as well as tool wear rates, and surface integrity. The cutting temperature, which is the cause of several problems restraining productivity, quality and hence machining economy, can be controlled by the application of high-pressure coolant (HPC) jet. High-pressure coolant (HPC) jet cooling is a promising technology in high speed machining, which economically addresses the current processes, environmental and health concerns. The benefits of reduction in machining temperature are reduction in cutting force, tool wear and surface roughness. This benefit of HPC cooling depends on the process parameters and cutting tool.
In this research work turning of AISI 1040 hardened steels (40 HRC, 48 HRC, 56 HRC) with HPC condition has been investigated and its performance is evaluated on the basis of chip morphology, surface finish, flank wear and cutting temperature. An effort is made to investigate the effect of cutting parameters (cutting velocity, feed and depth of cut) and the cutting environment on cutting performance. The cutting oil has been delivered through a specially designed and developed nozzle in such a way so that it can deliver oil jet at critical zones during hard turning. An investigative comparison with dry and HPC under same conditions has been done to evaluate the relative performance of hard turning with HPC jet. A model of tool wear was also developed for specific working condition. The model is developed to estimate the amount of principal flank wear with machining time for any one of the tool-work combinations and cutting environments. The experimental results indicate that the performance of the machining under HPC condition is quite good and more effective compared to machining under dry condition. With the help of the experimental results, model of principal flank wear has been developed to understand the basic phenomenon in metal machining. Finally the model was validated with experimental results to make it an acceptable model.
... Several studies have investigated the capability of the process to compete with grinding, and most have concluded that at proper conditions with a good machine, hard turning can produce dimensional accuracy and surface finishes acceptable for most applications. Matsumoto et al. [1986] were able to hard turn parts with surface finish ranging from 0.045-0.197 µm, and surface waviness from 0.775-1.26 ...
... This was verified by Brinksmeier et al. [1982] and Konig et al. [1993]. As expected, the magnitude and depth of residual stresses are a function of tool geometry and process conditions [Matsumoto et al. 1986, Tonshoff et al. 1995, Brinksmeier et al. 1982and Thiele 1998]. ...
Modern manufacturing industries are seeking different alternatives to attain the need of higher machining speeds, lower wastage and a better product quality as well as reducing the cost of the manufacturing process.An approach to this problem is considering high speed machining but high speed machining at high speeds and feeds generates large heat and high cutting temperature, which shortens the tool life and deteriorates the job quality. To reduce this high temperature machining of hardened medium carbon steelneeds large quantities of cutting fluid to be applied which not only incur expenses but also can cause grave environmental and health hazards. Dry machining might be an alternative in this context and is totally free from the problems associated with cutting fluid but is difficult to implement on the existing shop floor as it needs ultra-hard cutting tools and extremely rigid machine tools. The manufacturing industries hence are looking to mitigate these problems by experimental investigations and by adoption of advanced techniques such as cryogenic cooling, high-pressure coolant, and minimum quantity lubricant (MQL) application. Among these, Minimal Quantity Lubrication machining is found to be quite effective in improving tool life and surface finish.
In this research work surface milling of AISI 4140 steel (40 HRC)was investigated with pulsed jet Minimum Quantity Lubricant (MQL) applicator using straight oil as the cutting fluid. The investigation was carried upon comparing the performance of MQL applicator on the basis of tool wear, cutting force, and surface finish. The effects of different cutting parameters were compared at different combinations of feed, depth of cut and cutting conditions. A pulsed jet MQL applicator was designed and developed with the help of full factorial analysis (Design of Experiment) and it was ensured that the cutting fluid can be applied in different timed pulses and quantities at critical zones during surface milling.An investigative comparison with dry milling under same conditions has been done to evaluate the relative performance of hard milling with MQL applicator. It was observed that the MQL applicator system for surface milling on hardened steel can bring forth better performance when compared to dry milling.
... Lower cutting force, residual stress, reduced cycle time and mainly low energy consumption, are some of those advantages [2,3]. Research in this area has often focused on the choice of appropriate cutting tool materials, with results typically indicating that CBN tools perform better than carbides or alumina based tools [4][5][6][7]. Under proper conditions, CBN tooling can easily pay for its expensive initial cost with substantial tool life. ...
... Flank wear has been found to be the most significant factor affecting the depth of white layer [8]. Similar detrimental effects on residual stresses and white layers have been found by others [1,4,6,9]. ...
A basic difference of hard turning from conventional turning lies in its larger
specific cutting forces requirements which in turn can be lowered by applying no
cutting fluid. The beneficial effects of hard turning can be offset by excessive
temperature generation which causes rapid tool wear or premature tool failure if
the brittle cutting tools required for hard turning are not used properly. Under
these considerations, the concept of high-pressure coolant (HPC) presents itself
as a possible solution for high speed machining in achieving slow tool wear while
maintaining cutting forces at reasonable levels, if the high pressure cooling
parameters can be strategically tuned. This paper deals with an experimental
investigation of some aspects of the turning process applied on hardened steel
(HRC 56) using coated carbide tools at high cutting speeds under high-pressure
coolant, comparing it with dry cut. The results indicate that the use of high pressure coolant leads to reduced surface roughness, delayed tool flank wear,
and lower cutting temperature, while also having a minimal effect on the cutting
forces.
... Lower cutting force, residual stress, reduced cycle time and mainly low energy consumption, are some of those advantages [2,3]. Research in this area has often focused on the choice of appropriate cutting tool materials, with results typically indicating that CBN tools perform better than carbides or alumina based tools [4][5][6][7]. Under proper conditions, CBN tooling can easily pay for its expensive initial cost with substantial tool life. ...
... Flank wear has been found to be the most significant factor affecting the depth of white layer [8]. Similar detrimental effects on residual stresses and white layers have been found by others [1,4,6,9]. ...
... As an early application of analytical model, Liu and Barash [8] provided qualitative interpretation for residual stress in machining based on the line element subjected to elastic-plastic loading and unloading. Furthermore, Matsumoto et al. [9,10] investigated the effect of workpiece hardness on residual stress, employing Merwin and Johnson's model [11] on rolling contact for quantitative discussion. Following Merwin's analytical method, Jacobus et al. [12] developed a thermoelastoplastic model based on presumed deformation fields. ...
... It is well known that the mechanical-thermal effects give rise to the residual stress in machined surface. Although thermal load affects residual stress significantly in grinding and electrical discharging machining process, several reports confirmed that mechanical effect is the dominant factor for residual stress in the orthogonal machining of steels with gentle cutting conditions and that the effect of temperature rise is secondary [10,[29][30][31]. In this paper, mechanical load is assumed to be the dominant factor of residual stress generation and thermal effects are ignored for simplification. ...
Residual stress, characteristic of surface integrity, is a great issue in cutting process for its significant effects on fatigue life and dimension stability of the machined parts. From a practical viewpoint, residual stress is generated in a dynamic tool-part engagement process, instead of a process with nominal cutting loads. This is the challenge that we have to handle, so as to achieve better predictive methods than the previously recorded approaches in literatures which ignore the dynamic effects on residual stress. This paper presents an analytical method for the prediction of residual stress in dynamic orthogonal cutting. A mechanistic model of the dynamic orthogonal cutting is provided, considering the indentation effect of the cutting edge during the wave-on-wave cutting process. Following the calculation of plastic strains by incremental analysis in mechanical loading, analytical solution of the residual stress due to distributed plastic strains in half-plane is obtained based on inclusion theory. Without relaxation procedures, the two-dimensional (2D) distribution of residual stress in dynamic cutting process is predicted for the first time. A delicately designed dynamic orthogonal cutting experiment is realized through numerical control (NC) lathe. The periodic residual stress distribution is predicted using the proposed approach, which is then validated against the X-ray diffraction measurements.
... Several analytical models for residual stress in machining had been proposed since the early work of Liu et al. [8][9][10], which illustrated an idealized qualitative model with a small line element subjected to elastic-plastic loading and unloading process for the interpretation of residual stress. Matsumoto et al. [11,12] employed Merwin and Johnson's analytical method for rolling contact Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ijmecsci [13] to analysis the effect of workpiece hardness on residual stress. ...
... The tensile layer generated near the machined surface is achieved by both the analytical model and the FEM model. Base on the linear relationship between the residual stresses and the plastic strains in axial and circumferential direction, it is found that considerable tensile residual stress can also be generated when compressive plastic deformation is dominant in the cut direction even if the thermal effects are not considered, which was demonstrated in the pioneer work on the mechanism of residual stress [11,12] and the numerical analysis by [20,36]. However, the compressive peak around 50 μm in subsurface is not obtained in the analytical and numerical predictions. ...
Prediction of the residual stresses in machining is significant for the manufacturing of high performance components. This paper presents a novel relaxation-free analytical method for residual stress prediction in orthogonal machining based on the inclusion theory. First, a semi-analytical approach is employed for incremental analysis of the elastic-plastic deformation of the subsurface material. Both the mechanical loads on the shear plane and the flank face are considered in the contact model of orthogonal machining. Then, one-dimension distributed inclusion theory is deduced to achieve the closed-form solution of the residual stresses based on the plastic strains obtained in the foregoing analysis. Using the proposed method the boundary conditions encountered in the solution of the residual stress are satisfied in nature and the relaxation procedure is no longer required. A widely used orthogonal machining test is adopted to verify the residual stress derived from the proposed method. As a result the residual stress predicted by the proposed method is identical with the one from the relaxation procedure. Moreover, the proposed relaxation-free method is valid against the experimental measurement and the existing numerical simulation. In addition to the high computation efficiency inherited from analytical approach, the relaxation-free method provides a more concise solution with clear physical mechanism, which reveals the unique linear mapping relationship between the biaxial in-plane plastic strains and residual stresses in machining for the first time.
... The simultaneous application of laser and ultrasonic vibration energies was able to generate lesser machining forces and higher microhardness due to the separation characteristics and thermal softening phenomenon which eventually led to higher compressive residual stresses when compared with other processes. Higher compressive residual stresses were found to be obtained due to the higher microhardness, according to Matsumoto et al. 40 Thus, it can be concluded that the combined application of both the phenomenon regarding laser and ultrasonic vibration energies during the turning process led to higher compressive residual stresses than the individual processes. ...
Surface integrity of the machined surface is an important aspect considering their surface alterations, metallurgical effects, and mechanical characteristics during the machining process. Industries have been seeking a capable machining technology that can improve the machining process capabilities especially in an eco-friendly manner. Hybrid machining processes have shown significant improvement in machining performance when compared with the conventional turning (CT) process without using any cutting fluids. Moreover, a recently developed hybrid machining technology, that is, ultrasonic-vibration-laser assisted turning (UVLAT) has shown better machinability than the CT process. Therefore, an attempt has been made to improve the surface integrity of aluminum 3003 alloy in terms of machining forces, surface roughness, surface damage, microstructure, microhardness, residual stresses, and corrosion behavior during the UVLAT process. A comparative surface integrity analysis has been performed among the CT, ultrasonic vibration assisted turning (UVAT), laser assisted turning (LAT), and UVLAT processes. Significant improvement in the surface integrity has been observed for the aluminum 3003 alloy during the UVLAT process in comparison to the CT, UVAT, and LAT processes. The periodic separation of the cutting tool and thermal softening of the workpiece material, simultaneously during the UVLAT process is the possible reason for the improvement in surface integrity. Results demonstrated that the UVLAT process has an excellent potential to enhance the surface integrity of aluminum alloys and is better than the CT, UVAT, and LAT processes.
... In addition, the physical and mechanical properties of the surface layers after processing are determined by consolidation, depth of consolidation, distribution and degree of consolidation, structure of the consolidation layer, and residual stresses. The concept of surface integrity, originally defined for grinding operations, can be extended to other finishing operations and includes six different groups of key factors: visual, dimensional, residual stress, tribological, metallurgical, and other factors [13][14][15][16]. It should be noted that all parameters in the material removal process have a direct impact on the integrity of the machined workpiece surface [13,17,18]. ...
Reliable measurement of surface roughness (Ra) is extremely important for quality control of production processes. The cost of the equipment and the duration of the measurement process are very high. The aim of this work is to develop a device for non-destructive measurement of specific roughness levels on stainless steel using computer vision. The device should be structurally simple, affordable, accurate, and safe for practical use. The purpose of the device is to effectively detect the level of roughness of the treated surface obtained by the water jet cutting process. On the basis of the obtained results, it is possible to adjust the parameters during the cutting process. The principle of operation of the device is based on measuring the intensity of the visible spectrum of the light reflected from the surface of the sample to be measured and correlating these values with the values of the measured roughness. After testing several variants of the device, the so-called vertical measurement variant was developed using the following equipment: violet light LED, optical filter and light splitter, USB 2.0 web camera, Arduino microcontroller, personal computer, and LabView programming interface.
... Using Hertz theory, Merwin and Johnson [5] conducted early analytical work to predict RS in rolling contact under plane strain conditions. Matsumoto et al. [6] extended the classical Hertz theory by considering both the normal contact stresses and the shear contact stresses. Jacobus et al. [7] developed a plane strain thermo-elastoplastic model to predict the full in-plane biaxial RS profiles for turning of annealed AISI 4340. ...
Background
Efficient and reliable prediction of machining-induced residual stress (RS) is a key requirement for truly integrated computational materials engineering (ICME). Currently available process modeling approaches, including empirical, analytical, and numerical methodologies lack predictive power and require substantial calibration and validation data. Moreover, most model-based approaches consider only two-dimensional (2D) (i.e., orthogonal), cutting processes. Meanwhile, industrial processes such as milling, turning, and drilling are inherently three-dimensional (3D).Objective
The present work attempts to bridge the gap between 2D and 3D RS simulation in machining through careful consideration of the process physics, including geometric, kinematic, and size-effect constraints to realize robust prediction of how RS develops in 3D machining. Using a novel in-situ experimental technique and digital image correlation (DIC) to determine equivalent Hertzian contact widths, contact pressures, and friction coefficients, the proposed methodology leverages a discretized conversion algorithm that includes multi-pass shakedown effects.Methods
This paper presents a semi-analytical model to predict machining-induced RS in 3D turning operations, which are used representatively for 3D processes more generally. Rather than follow a ‘brute force’ 3D FEM approach or conduct countless experiments to train a purely data-driven machine learning algorithm, the proposed approach builds on previous 2D modeling work. Through careful consideration of the process physics, including complex geometry/kinematic considerations of 3D turning, the authors demonstrated an experimentally calibrated approach, as well as validation based on published RS data.ResultsModel predictions and previously published measurement data of RS depth profiles for turning of Inconel 718 were compared for a range of process parameters. Correlation between the proposed 3D model and validation data was found to be within the margin of experimental error for most conditions. The proposed model appears to capture the overall behavior of 3D RS depth profiles with acceptable accuracy, particularly the key metrics of near-surface stress, peak stress magnitude and location, as well as overall stress profile depth.Conclusion
This paper presents a physics-informed, data-driven approach for efficient calibration of a 2D model for machining-induced RS through DIC analysis of in-situ characterized subsurface displacement fields.
... These results can be explained by the effect of an increase in thermal dominance in machining with a higher feed rate under dry machining. Matsumoto et al. (1986) studied the effect of hardness of the steel on machine-induced residual stresses in AISI 4340 steels with a sharp tool and a chamfer tool. ...
... Lima et al. [1] noticed that the cutting force decreased slightly when the hardness of AISI 4340 steel was increased from 250 to 345 HV, but increased with a further elevation to 415 HV, while the feed and thrust forces increased steadily with workpiece hardness. This behavior, also reported by Matsumoto et al. [2], can be explained by the fact that the increase in the shear strength of the work material is counterbalanced by the smaller chiptool contact area. ...
Owing to their inferior hot hardness in comparison with alumina-based ceramics and polycrystalline cubic boron nitride, the performance of coated carbide tools when turning hardened steels strongly relies on proper chemical composition and carbide grain size, together with adequate cutting edge preparation. This work investigates the effect of geometric parameters on the performance of cutting tools applied to turning of AISI 4140 steel hardened to 40 and 50 HRC, in terms of the components of the turning force and temperature. Additionally to well-established geometric parameters, such as the projection of the hone radius on the rake face (Sγ), the projection of the hone radius on the clearance face (Sα), and the form factor K (ratio of Sγ to Sα), a novel parameter is proposed, namely perimeter ratio (P), which represents the ratio of the perimeter of the modified cutting edge to the circumference of the standard honed edge. Moreover, the experimental results were compared with analytical and numerical findings in order to assess their effectiveness in predicting the components of the turning force and chip temperature. The results indicated that analytical modeling was capable to satisfactorily predict the variation of the force components with edge preparation, using as input the value of the corresponding experimental forces for the standard honed cutting edge. On the other hand, the numerical modeling was successfully applied to predict the components of the resultant force at the expense of higher computational effort. The cutting force was not drastically affected by edge preparation, whereas the feed and passive forces increased with P and Sα and the form factor K was not capable to provide a consistent relationship with both the feed and passive forces. Both the experimental and numerical temperatures of the chip and the numerical temperature at the tool-chip interface did not present a straightforward trend with regard to edge preparation.
... The thermomechanical hardening process generates a better-hardened layer and it will be a cost-effective method than other conventional hardening processes with special benefits like less production cost, waste reduction and minimize the cycle time [14]. It has been depicted that when the machined surface of AISI 4340 steel material's hardness value was more than 50 HRC, the segmentation type chips were formed [15]. The surface hardness of AISI 4340 steel enhanced by the ion nitriding treatment process increases the time and temperature. ...
Turning of hardened AISI 4340 steel is regarded as one of the demanding challenges in machining sectors where precision tolerances are essential for automobile parts. The AISI 4340 steel is broadly utilized in forged steel automotive crankshafts systems, hydraulic forged and additional machine tool purposes because of their improved characteristics. Moreover, one of the keys confronts in the machining of hard 4340 steel is the comparatively deprived machining behavior that reduces the functionality of the material and further leads to component rejection at the final inspection stage. In addition, accelerated tool wear necessitates for repeated changing of cutting tool that results in higher machining and tooling costs. This comprehensive review aimed to present in-depth features on the development of machining performances using various cutting tools. This review focus is to provide a broad perceptive of the role of controllable variables during machining of hardened steel. This review analysis examines the response variables and their advantages of chip morphology and heat generation. The comprehensive overview of machining settings, key machinability indicators and statistical analysis for AISI 4340 steel. This overview will provide academic, industrial and scientific communities with benefits and shortcomings through improved conceptual understanding towards further research and development.
... Wu and Matsumoto [1990] showed that shear angle effects dominate the stress patterns in facing of AISI 4340 steel of different hardness values. Matsumoto et al. [1986] also reported similar observations when examining the effect of workpiece hardness on residual stress produced in facing of AISI 4340 steel. They have studied total seven level of hardness ranging from HRC 29 to HRC 56 and showed that, in the absence of phase transformations, residual stresses become more compressive as workpiece hardness increased. ...
Machining induced residual stress is an important aspect of study on controlling machining parameters to get desired product quality as the functional behavior of machined component can be enhanced or impaired by it. Besides, high pressure coolant (HPC) supply during machining is considered as favorable cutting environment to get better machinability indices over dry condition. In the purpose of gaining superior product quality it would be beneficial to study the effect of residual stress under HPC condition along with rational setting of machining parameters.
This study aims at finding the optimum cutting conditions and monitoring the residual stress in turning of 42CrMo4 alloy steel by HPC lubrication. On the basis of experimental results this paper develops empirical models for predicting cutting temperature, surface roughness and tool wear in terms of workpiece hardness, cutting speed and feed rate using multiple regressions modeling method. The results of ANOVA prove that the models could adequately describe the performance indicators within the limits of the statistical factors. Then, multi-objective optimization approach based on genetic algorithm has been employed to get the optimal setting of process parameters that simultaneously minimize cutting temperature, surface roughness and tool wear. It was found that the optimum results provide consistent results compared to experimental measurements. The optimum results was then used in finite element method based simulation of residual stress. This paper presents a 2D finite element model based on Arbitrary-Lagrangian-Eulerian formulation using ABAQUS software. The Johnson-Cook material and damage model have been used for chip formation. Based on this model the effects of coolant application on temperature variation were investigated in simulations. The temperature distribution of chip-tool interface in simulation shows a good agreement with the measured cutting temperature. Simulation results offer an insight into workpiece hardness and cutting parameters influence on the induced residual stresses. Based on the simulation results, cutting speed and workpiece hardness show trend for machining induced residual stress. However, more investigation is needed in determining a trend for the feed rate influence.
... Several studies have investigated the capability of the process to compete with grinding, and most have concluded that at proper conditions with a good machine, hard turning can produce dimensional accuracy and surface finishes acceptable for most applications. Matsumoto et al. [1986] were able to hard turn parts with surface finish ranging from 0.045~0.197 µm and surface waviness from 0.775~1.26 ...
The generation of huge amount of heat in high production machining at high cutting velocity and feed rate shortens the tool life and deteriorates the job quality. The conventional cutting fluids are not that effective in such high production machining particularly in continuous cutting of materials like steels. Because of these some alternatives has been sought to minimize or even avoid the use of cutting fluid in machining operations. One of these alternatives is machining with minimum quantity lubricant (MQL). It is a mixture of impinging of least amount of cutting fluid along with highly compressed air through a small nozzle results in reducing the heat produced during metal cutting. The main objective of the present work is to make an experimental investigation on the role of MQL in turning hardened steel by uncoated carbide insert (SNMG 120408) in respects of chip formation, chip-tool interface temperature, tool wear and surface roughness. The result indicated that the machining with MQL performed much better than dry machining mainly due to reduction in cutting zone temperature enabling favorable chip-tool interaction. This also facilitated the reduction in tool wear in leading to enhance tool life and surface finish.
... Precision hard turning applications have increased drastically in manufacturing industry because it potentially provides an alternative to conventional grinding in machining hardened components. This new technology significantly reduces the production time, tooling costs and the capital investment [Matsumoto et al., 1986], especially for low volume production. With grinding, it is typically necessary to rough the material on a lathe then send it to a heat treatment operation and after that it requires several grinding operations to finish it. ...
Machining of pre-hardened steel materials, known as hard turning, is gaining more and more attention recently because it offers numerous advantages over traditional grinding in some applications. In addition it differs from conventional turning process since it possesses some special behaviors such as chip breakability and micro structural alteration at the machined surfaces. Typically no cutting fluid is applied during hard turning in order to minimize both cutting forces and environmental impacts. Minimum quantity lubrication (MQL) which refers to the use of small amount of cutting fluid addresses itself as a viable alternative for hard machining with respect to tool wear, heat dissertation, cutting force generation and machined surface quality. The present research work is divided into two parts. First of all there is an experimental analysis of the effects of minimum quantity lubrication on cutting zone temperature, main cutting force, chip thickness ratio tool wear and surface quality of the machined part while turning hardened steel (56 HRC) material with coated carbide insert. The results indicated that the application of MQL technique significantly helps to obtain better result in compare to dry condition. The other part of the research work is concentrated to the optimization of cutting parameters (cutting speed, feed rate and depth of cut) while turning hardened medium carbon steel by coated carbide insert under MQL condition. Optimization was done using genetic algorithm. The objective function of the optimization process was to determine the cutting parameter that minimizes surface roughness under certain constraints. Statistical models using multiple regression analysis under Response Surface Methodology (RSM) have been developed to establish the objective function and also the constraints for solving the problem. The developed models satisfactorily validate its accuracy by drawing desirable experimental results.
... Precision hard turning applications have increased drastically in manufacturing industry because it potentially provides an alternative to conventional grinding in machining hardened components. This new technology significantly reduces the production time, tooling costs and the capital investment [18], especially for low volume production. Koning [19] also presented that turning of hardened steels have been an attractive alternative to costly, yet environmentally harmful, grinding processes. ...
Hard turning is a profitable alternative to finish grinding in respect of dimensional accuracy and surface finish to fulfill functional requirement, improved performance and prolonged service life of the product. Hard turning is able to reduce processing time, production cost, surface roughness and setup time appreciably in comparison to grinding. But high heat generation at high production machining increase tool wear and deteriorates the job quality. The conventional cutting fluids are not that effective in such situation. Minimum quantity lubrication (MQL) is a suitable alternative in this regard.
In this research work, the effects of MQL on cutting performance of hardened AISI 4320 steel in respect of chip formation, chip-tool interface temperature, tool wear and product quality have been studied using coated carbide insert (SNMG-TN 4000). Three types of cutting fluids (soluble oil, vegetable oil and VG 68 cutting oil) have been used to compare the relative performance of those cutting fluids with each other as well as with that of dry condition.
Compared to dry condition, MQL performed better mainly due to substantial reduction in cutting temperature that enabling favorable chip-tool interaction. This also facilitated the substantial reduction in tool wear, dimensional inaccuracy and surface roughness. The results indicated that the use of minimum quantity lubrication (MQL) by VG 68 cutting oil performed better in comparison to other cutting fluids in respect of chips formation mode, cutting temperature, tool wear, surface roughness and dimensional deviation.
... Several studies have investigated the capability of the process to compete with grinding, and most have concluded that at proper conditions with a good machine, hard turning can produce dimensional accuracy and surface finishes acceptable for most applications. Matsumoto et al. [11] were able to hard turn parts with surface finish ranging from 0.045-0.197 µm, and surface waviness from 0.775-1.26 ...
A difficult-to-cut material like hardened steel is used predominantly in the automotive and bearing industries due to its exceptional corrosion and thermal resistance and high shear strength. Abrasive machining processes such as grinding have typically been required to machine hardened steels, but advances in machine tools and cutting materials have allowed hard turning on modern lathes to become a realistic replacement for many grinding applications. Despite so many advantages, implementation of hard turning remains relatively low, primarily due to concerns about the quality of hard turned surfaces and a lack of understanding about the wear behavior of cutting tools. In general, the most important point in machining processes is the productivity, achieved by cutting the highest amount of material in the shortest possible time using tools with the longest lifetime. Combining all the parameters involved in the machining process to maximize productivity is, nevertheless, a very complex task and becomes much more difficult when working at high speed machining in hardened steels. To address this concern, this research investigated the effects of changing process conditions on wear behavior when turning hardened medium carbon steel (56 HRC) with coated carbide cutting tools.
The aim of this research is to investigate the influence of feed rate and cutting speed on the wear behavior of both SNMG and SNMM coated carbide inserts under high pressure coolant condition. Investigation on the effect of high pressure coolant on the machined chip, cutting temperature, cutting forces and product quality is the prime intention of this research.
To become a realistic replacement for grinding operation, surface roughness produced by hard turning must be comparable to grinding process if hard turned surfaces are to be accepted. Steady and progressive surface roughnesses with dimensional deviation have been investigated in this research work. The results indicate that proper selection of machining condition and high pressure cooling system yields acceptable dimensional accuracy and surface quality. It also allows adequate tool life by keeping the cutting zone temperature and cutting forces at lower levels.
... The surface machined by the first cutting tool was work hardened and hence the hardness was increased. Matsumoto et al. [31] reported that the hardness of AISI 4340 steel increased from HRC 54 to HRC 58 during cold working. The trend of increased residual stresses on increasing the cutting speed and feed of the second cutting tool remains same as first cutting tool except the difference in magnitude. ...
In this paper numerical study was performed to evaluate the surface residual stresses in duplex turning process. A computational model was created using commercially available software ABAQUS 6.14. The chip separation was based on Johnson-Cook damage criteria. Penalty contact approach was used to model the friction between the chip and the cutting tools. The effect of process parameters such as cutting speed and feed on circumferential and axial residual stresses was investigated. The surface residual stresses increased with the increase in cutting speed and feed. The numerical results indicated that higher circumferential and axial compressive residual stresses are induced on the surface machined by second cutting tool when simultaneously machined along with the first cutting tool. The duplex turning process proved advantageous in increasing the compressive surface residual stress.
... The mechanics of chip formation when machining hardened steels at high cutting speeds have been researched by Komanduri et al. [18] and Shaw [19]. Wu et al. [20] and Matsumoto et al. [21] studied the effects of workpiece hardness on the machined workpiece surface quality. They identified that the stress field generated in the workpiece determined the residual stress. ...
Methods of the optical metallography, TEM, SEM-technique, tests for hardness and wear resistance are used to investigated the structural - phase transformation in metal blanks from alloy VT23 at cutting treatment in an interval of speeds 2...120 m/min are given. The patterns of interaction of dynamic plastic deformation and destructions on macro-, meso-, micro-and nanolevels are determined. It is shown that the formation in metal blank of modulated high-tensile secondary nanostructures promotes a heightening of a protective wearproofity of treated metal blank, but cutting edge, lowering a wearproofity, of the cutting tool.
... It was reported that since the method of machining hardened steel differs from that of machining soft steel, the machined surface of soft steel does not show any stage of phase transformation. Authors in [15] reported a case of deformation in machined surfaces of hardened steels and found that the residual stresses in soft steels are mostly tensile stresses while those remaining in hardened steels are mostly compressive stresses. Another research which was conducted on two types of steel which have been machined by turning reported that residual stresses are influenced, to a great extent, by feed rate and nose radius and, to a certain extent, by the cutting speed and the rake angle. ...
The influence of some turning variables and tool overhang on surface roughness parameters and residual stress induced due to machining 6061-T6 aluminum alloy is investigated in this paper. Four input parameters (cutting speed, feed rate, depth of cut and tool overhang) are considered. Tests are carried out by precision turning operation on a lathe. Design of experiment techniques, i.e. response surface methodology (RSM) and Taguchi's technique have been used to accomplish the objective of the experimental study. Surface roughness parameters are measured using a portable surface roughness device while residual stresses are measured employing deflection-etching technique using electrochemical analysis. The results obtained reveal that feed and rotational speed play significant role in determining the average surface roughness. Furthermore, the depth of cut and tool overhang are less significant parameters, whereas tool overhang interacts with feed rate. The best result of surface roughness was obtained using low or medium values of overhang with low speed and /or feed rate. Minimum maximum tensile residual stress can be obtained with a combination of tool overhang of 37 mm with very low depth of cut, low rotational speed and feed rate of 0.188 mm/rev.
... Extended research on the mechanisms of residual stress creation, concluded that mechanical forces are the main cause and the thermal stresses load is insignificant. Matsumoto et al. 1 while studying the effect of hardness on residual stresses carried out machining experiments in a treated material with 57 HRC. The results revealed that, when hardness and other cutting parameters remain constant, the plastic deformation near the cutting edge is a dominant factor in the creation of residual stresses profile. ...
This work was based on the surface integrity analysis of hardened steel, AISI 4317 case carburized, quenched and tempered with 58 HRC, obtained by a turning operation executed with CBN (cubic boron nitride) tool, varying three basic cutting parameters (cutting speed, feed rate and cutting depth). The surface integrity characterization was conducted analyzing the behavior of the surface roughness Ra, residual stresses and with layer presence after turning. Also, the cutting forces were measured. The experimental planning used was a central composite design. The results and data were statistically treated by the Statistica software, enabling the generation of a mathematical model, relating the dependent variables with the independent variables. The roughness values Ra obtained after the experiments ranged from 0.31 to 2.8 µm, providing an indication that is possible to replace grinding process by hard turning using CBN tools that could reduce machining time and costs. The hard turning process generated compressive residual stresses profiles and white layer formation, from 1.1 to 5.1 µm, on the surface of the samples. The penetration force showed the highest values for the turning forces measurements. The lowest values for the cutting parameters represented the optimized surface integrity of the AISI 4317 steel.
... It was found that the surface residual stress changed from tensile stress to compressive stress in the cutting process. As the microhardness increased, it changed the distance from the peak of residual compressive stress to surface [13]. ...
In the multi-step cutting process, the final machined surface quality is affected by the entire cutting process, especially the effect of work hardening and thermal softening induced by the previous steps (roughing or semi-finishing machining). In this paper, two-step (roughing-finishing) and three-step (roughing-semi-finishing-finishing) turning operations were designed by a single-factor experiment, and the effect of the change of cutting parameters in the previous steps on finishing surface quality was analyzed. Experimental results indicated that the microhardness in the machined surface layer of semi-finishing was smaller than that of roughing at the same depth, and the depth affected by work hardening of semi-finishing was thinner. Therefore, compared to two-step machining, the surface roughness affected by the work hardening and thermal softening of the previous steps was smaller after three-step machining, and the variation range of surface roughness with the change of the cutting parameters was smaller. Moreover, the relative height between the convex peak and the concave valley was larger. And the spacing between adjacent two convex peaks became larger and more uneven after three-step machining. The disturbed layer depth or the plastic deformation layer (PDL) depth was obviously reduced. However, the grains were severely distorted and stretched. It was because that semi-finishing weakened the work hardening of roughing in the three-step cutting process; therefore, the surface quality was better after finishing. By studying the effect of work hardening and thermal softening induced by the previous steps on finishing surface quality, the cutting parameters of roughing and semi-finishing were optimized to ultimately improve surface quality.
... There is a martensitic phase transformation in the near surface structures, yielding surface or near surface elements due to thermal stresses caused by machining heat, and uneven plastic deformation of surface or subsurface elements. Under usual situations, when there is no excessive tool wear or abusive machining practice, very little martensitic formation is observed in the machined surface layer of hardened steel [58]. The existence of untempered martensite on the subsurfaces produces a compressive residual stress due to its larger volume. ...
A correlation between machining process and fatigue strength of machined components clearly exists. However, a complete picture of the knowledge on this is not readily available for practical applications. This study addresses this issue by investigating the effects of machining methods on fatigue life of commonly used materials, such as titanium alloys, steel, aluminium alloys and nickel alloys from previous literature. Effects of turning, milling, grinding and different non-conventional machining processes on fatigue strength of above-mentioned materials have been investigated in detail with correlated information. It is found that the effect of materials is not significant except steel in which phase change causes volume expansion, resulting in compressive/tensile residual stresses based on the amounts of white layers. It is very complex to identify the influence of surface roughness on the fatigue strength of machined components in the presence of residual stresses. The polishing process improves the surface roughness, but removes the surface layers that contain compressive residual stresses to decrease the fatigue strength of polished specimens. The compressive and tensile residual stresses improve and reduce fatigue strength, respectively. Grinding process induces tensile residual stresses on the machined surfaces due to high temperature generation. On the other hand, milling and turning processes induce compressive residual stresses. High temperature non-conventional machining generates a network of micro-cracks on the surfaces in addition to tensile residual stresses to subsequently reduce fatigue strength of machined components. Embedded grits of abrasive water jet machining degrade the fatigue performance of components machined by this method.
... Contrary to the gradual trends exerted by speed-feed, the change of material hardness value severely affects the roughness profile, explicitly when the hardness steps to 56 HRC from 48 HRC. This issue is addressed by the fact that material of high hardness ($56 HRC) when machined endures excessive compressive stress [34] imposed by the tool exerted cutting forces. This phenomenon gives rise to the reacting force by the hardened material thus the chip deformation becomes harder. ...
In this study, an artificial neural network (ANN) based predictive model of average surface roughness in turning hardened EN 24T steel has been presented. The prediction was performed by using Neural Network Tool Box 7 of MATLAB R2015a for different levels of cutting speed, feed rate, material hardness and cutting conditions. To be specific the dry and high pressure coolant (HPC) jet environments were explored as cutting conditions. The experimental runs were determined by full factorial design of experiment. Afterward the 3-n-1, 3-n-2 and 4-n-1 ANN architectures were trained by utilizing the Levenberg-Marquardt (LM), Bayesian regularization (BR) and scaled conjugate gradient (SCG) algorithms, and evaluated based on the lowest root mean square error (RMSE). The 3-10-1 and 3-4-2 ANN models, trained by BR, revealed the lowest RMSE. A good prediction fit of the models was established by the regression coefficients higher than 0.997. At last, the behavior of the surface roughness in respect of speed-feed-hardness for dry and HPC conditions has been analyzed. The HPC reduced surface roughness by the efficient cooling and lubrication whereas the higher hardness of material induced higher average surface roughness due to higher restraining force against tool imposed cutting force.
... In machining processes, residual stresses can be attributed to three causes: martensitic phase transformation, thermal stresses due to machining heat, and mechanical effect because of uneven plastic deformation of material [10]. However, under normal machining conditions, formation of great quantities of martensite is usually not observed [8]. Both mechanical and thermal effects affect the deformation zone of the workpieces' surface, in a way that they are superimposed. ...
In the present paper, residual stresses induced by honing processes on hardened steel cylinders were determined. Cubic boron nitride (CBN) abrasives were employed. Both surface measurements and depth profiles were obtained by means of XRD. SEM observations were performed on samples’ surface. Roughness and material removal rate were also measured. Compressive residual stresses, which are known to increase fatigue life of components, were reported both in the axial and in the tangential direction. Shearing stresses were negligible. If only rough honing is taken into account, as a general trend, the lower cutting conditions used, the higher surface stresses are. A similar situation was found when only semifinish or only finish honing is considered. In most cases studied, stress profiles similar to those obtained in grinding processes, in which compressive stresses decrease with depth, were observed. However, in rough honing at hard cutting conditions, a typical hook-shaped profile was found with maximum compressive stress at 80-μm depth. Such shape is usual in turning processes. In order to obtain high surface stresses a rough, semifinish or finish honing operation with low cutting conditions is recommended. However, if stresses are to be obtained at a certain depth, rough honing at high cutting conditions is to be selected.
... If the load is too high, seizure will occur, but if all of these are avoided then the only alternative and viable cause of failure is due to the continuous accumulation of residual stress until spalling occurs. Such accumulation can be further enhanced by plastic deformation and strain or stress-induced phase transformations due to service load [38][39][40]. ...
Whereas considerable progress has been reported on the quantitative estimation of the microstructure of steels as a function of most of the important determining variables, it remains the case that it is impossible to calculate all but the simplest of mechanical properties given
a comprehensive description of the structure at all conceivable scales.
Properties which are important but fall into this category are impact
toughness, fatigue, creep and combinations of these phenomena.
The work presented in this thesis is an attempt to progress in this
area of complex mechanical properties in the context of steels, although
the outcomes may be more widely applied. The approach used relies
on the creation of physically meaningful models based on the neural
network and genetic programming techniques.
It appears that the hot–strength, of ferritic steels used in the power
plant industry, diminishes in concert with the dependence of solid solution strengthening on temperature, until a critical temperature is
reached where it is believed that climb processes begin to contribute. It
is demonstrated that in this latter regime, the slope of the hot–strength
versus temperature plot is identical to that of creep rupture–strength
versus temperature. This significant outcome can help dramatically
reduce the requirement for expensive creep testing.
Similarly, a model created to estimate the fatigue crack growth rates
for a wide range of ferritic and austenitic steels on the basis of static
mechanical data has the remarkable outcome that it applies without
modification to nickel based superalloys and titanium alloys. It has
therefore been possible to estimate blindly the fatigue performance of
alloys whose chemical composition is not known.
Residual stress is a very complex phenomenon especially in bearings due to the Hertzian contact which takes place. A model has been
developed that is able to quantify the residual stress distribution, under
the raceway of martensitic ball bearings, using the running conditions.
It is evident that a well–formulated neural network model can not only be extrapolated even beyond material type, but can reveal physical relationships which are found to be informative and useful in practice.
... Recent works on carbon steel have also shown that the nature of the residual stresses produced on a machined surface is related to the material properties, especially its hardness. Matsumoto et al. [5] showed that the residual stresses obtained from the machining of AISI 4340 steel are tensile for low hardness levels but become compressive as hardness increases. For the same material, Wu and Matsumoto [6] showed that the residual stress pattern is linked to the orientation of the primary shear deformation zone in metal cutting. ...
... Regarding cutting conditions, it is reported that feed rate has the highest impact on residual stresses [9]; an increase in feed rate results in higher compressive residual stresses. The effect of workpiece material, tool nose radius, tool wear and material hardness has been also investigated [9][10][11][12]. In another work, it argued that although feed rate is the major parameter that influences surface roughness, cutting speed is the major parameter that influences residual stresses level [13]; in the In Figure 5, the dependence of the maximum compressive residual stress on the value of the rake angle can be clearly seen. ...
In precision manufacturing processes surface integrity is of the utmost importance for the performance and life-cycle of the final products. An important aspect of surface integrity is associated with residual stresses induced in the workpiece during machining. According to the relevant literature, tool rake angle plays an important role on the features of residual stresses, regarding their magnitude and distribution within the workpiece. In this paper, numerical investigations with the use of the finite elements method are presented that allow the evaluation of the influence of the tool rake angle on residual stresses for the case of hard turning of stainless steel. The investigation is performed in a wide range of positive and negative rake angles. Numerical results verify the dominant role of tool rake angle on the residual stresses. The proposed models can be used for the a priori evaluation of the characteristics of compressive stresses that are considered favorable for the produced components.
AZ31B magnesium alloys are significant materials for biomedical, aviation, and automotive industries. But, the poor surface properties of AZ31B magnesium alloys limit their usage for wider applications. Literature suggests that hybrid machining processes have achieved better machining performance compared to the conventional turning (CT) process without using any cutting fluids. Therefore, an attempt has been made to improve the surface integrity of AZ31B magnesium alloy in terms of machining forces, machining temperature, chip morphology, surface roughness, surface damage, microstructure, microhardness, residual stresses, and corrosion behavior during a recently developed hybrid machining technology, i.e., ultrasonic-vibration-laser-assisted turning (UVLAT). A comparative surface integrity analysis has been carried out among the CT, ultrasonic vibration-assisted turning (UVAT), laser-assisted turning (LAT), and UVLAT processes. The results of the current study indicate significant benefits of the UVLAT process on surface integrity. Machining forces and surface roughness were reduced by 42-61% and 18-33%, respectively, for the UVLAT process than the other processes. However, the machining temperature was increased by 8-83% during the UVLAT process compared to the other processes. Ductile chips, smooth surface, and higher grain refinement were obtained in the UVLAT process when compared with other processes. Residual stresses were found more compressive in nature for the UVLAT process than that of the other processes. Microhardness and corrosion resistance were increased by 28-106% and 13-56%, respectively, during the UVLAT process in comparison with the other processes. This might be ascribed to the frequent tool separation and workpiece material thermal softening, simultaneously. The UVLAT process can be beneficial for diverse applications due to the improvement in surface properties.
Ti-6Al-4V titanium is considered a difficult-to-cut material used in critical applications in the aerospace industry requiring high reliability levels. An appropriate selection of cutting conditions can improve the machinability of this alloy and the surface integrity of the machined surface, including the generation of compressive residual stresses. In this paper, orthogonal cutting tests of Ti-6Al-4V titanium were performed using coated and uncoated tungsten carbide tools. Suitable design of experiments (DOE) was used to investigate the influence of the cutting conditions (cutting speed Vc, uncut chip thickness h, tool rake angle γn, and the cutting edge radius rn) on the forces, chip compression ratio, and residual stresses. Due to the time consumed and the high cost of the residual stress measurements, they were only measured for selected cutting conditions of the DOE. Then, the machine learning method based on mathematical regression analysis was applied to predict the residual stresses for other cutting conditions of the DOE. Finally, the optimal cutting conditions that minimize the machining outcomes were determined. The results showed that when increasing the compressive residual stresses at the machined surface by 40%, the rake angle should be increased from negative (−6°) to positive (5°), the cutting edge radius should be doubled (from 16 µm to 30 µm), and the cutting speed should be reduced by 67% (from 60 to 20 m/min).
Ball end magnetorheological finishing (BEMRF) is a nanofinishing process for finishing 3D surfaces of a large variety of materials such as glass, steel, copper, polycarbonates, silicon, etc. Under the influence of magnetic field, abrasive-laden ball of magnetorheological polishing fluid present at the tip of the tool removes material from the workpiece surface. The knowledge of forces associated with the process aids in understanding the material removal mechanism and the process physics. Also, the prediction of finishing spot plays a vital role in increasing the process capabilities of BEMRF process in the area of localized/selective finishing. In this work, a theoretical model of finishing forces is presented that helps in improving the in-depth understanding of the nanofinishing process. In addition to it, a theoretical model of finishing spot size is also proposed. Depending upon the area of workpiece to be finished locally/selectively, the finishing spot model provides a deterministic way to alter the size of finishing spot of BEMRF process by changing the finishing parameters.
The tribological properties and behaviors in the nanometric machining play a critical role in the high surface quality and low subsurface damage for the machined materials. However, in situ TEM experiments have the limitation of length and time scales to investigate the dynamic nanomachining process. Molecular dynamics (MD) simulation is widely employed to describe the nanomachining at atomic scale, and provides some dynamic deformation details which can be hardly revealed by the experiment. In this chapter, we review recent works on the nanometric machining to understand the tribological behaviour. The fundamentals of nanometric machining in term of the friction, material removal, tool wear, and lubrication, are discussed for deeply understanding of the physical mechanisms of nanomachining induced tribological behaviour.
AISI 304 stainless steel samples were milled with different feed rates and depths of cut. The effect of the milling parameters on the surface residual stresses was assessed by x-ray diffraction. The chemical composition of the passive film was examined by x-ray photoelectron spectroscopy. The corrosion behavior and pitting corrosion susceptibility in 3.5 wt.% NaCl solution were investigated by potentiodynamic polarization curves. The Mott–Schottky approach was employed to study the semiconducting properties of the passive films. Milling imparted higher surface stresses to the metal surface. Compressive stresses were favored at slower feed rates and higher depths of cut. Chromium enrichment was observed after milling, leading to an increased stability of the passive film for the milled samples with respect to the as-received material. The corrosion behavior and doping densities of the passive films were also affected by milling. There is a strong relationship between milling parameters, surface stresses, chemical composition of the passive film and its corrosion behavior.
Metal working fluids (MWFs) play an important role in the machining processes by providing proper cooling and lubrication. The life of tool as well as the power consumption during machining can be minimized by applying cutting fluid at the chip–tool and flank–work tribological interface. Besides, the cutting fluid carries away the heat produced at the machining zone as well. Different types of conventional metal working fluids are used in the machining processes. Nevertheless, the selection of metal working fluid depends upon the machining condition as well as the work–tool combination. Most of these MWFs are prepared from unsustainable crude oil extracts, which possess serious issues related to the air and water pollution; operators' health, increased cost of recycling, storage, and disposal of cutting fluids. The negative effect of conventional cooling can possibly be countered by using latest lubricoolant techniques. This chapter mainly deals with the overview of the lubricoolant techniques such as high-pressure jet minimum quantity lubrication (MQL), nanoparticles-based MQL, and cryogenic cooling techniques. The present study also discusses about the tribological and thermal aspects of various lubricoolant techniques. The comparison of all the techniques to highlight the benefits and its sustainability in metal cutting has been shown by conducting a case study on the machining of nickel-based Inconel 718 alloy. The results show that the cryogenic and nanoparticles-based MQL are the most promising cooling and lubrication technique. A 23.5% reduction of cutting force is recorded when nanoparticle-based MQL was used, and 16.75% reduction of cutting force was obtained in cryogenic cooling.
Part I of these two-part papers will investigate the effect of three FEM representations of the milling process on the prediction of chip morphology and residual stresses (RS), when down-milling small uncut chips with thickness in the micrometer range and finite cutting edge radius. They are: i) orthogonal cutting with the mean uncut chip thickness t, obtained by averaging the uncut chip thickness over the cutting length, ii) orthogonal cutting with variable t, which characterizes the down-milling process and which is imposed on a flat surface of the final workpiece, and iii) modelling the true kinematics of the down milling process. The appropriate constitutive model is identified through 2D FEM investigation of the effects of selected constitutive equations and failure models on the prediction of RS and chip morphology in the dry orthogonal machining of Ti6Al4V and comparison to experimental measurements. The chip morphology and RS prediction capability of these representations is assessed using the available set of experimental data. Models featuring variable chip thickness have revealed the transition from continuous chip formation to the rubbing mode and have improved the predictions of residual stresses. The use of sequential cuts is necessary to converge toward experimental data.
Residual stress is induced in a workpiece’s surface layer by machining, which badly affects the components’ static strength, fatigue strength, and corrosion resistance. In this study, experiments are conducted based on a response surface methodology (RSM) using Box - Behnken experiment design. Surface residual stress measured by the X-ray diffraction method and the test results were analyzed using variance analysis. The paper proposes a mathematical model of the influence of cutting parameters such as cutting speed, feed rate, depth of cut on surface residual stress.
Steels are susceptible to surface- and subsurface-related degradations (e.g. corrosion and wear) depending upon the working environment; however, desired properties can resolve these issues. The authors have selected the high-velocity oxygen-fuel process to develop alumina-based composite coatings on ASME SA 387 GR22 CL2 steel. The coating material chosen comprises ceria and hexagonal boron nitride as the reinforcements. The metallurgical characteristics of coatings are recorded using X-ray diffraction and scanning electron microscopy. Mechanical properties are mapped using a nano-indenter; and an air jet erosion test rig is used to evaluate erosion wear response. Improvements in the mechanical properties and erosive wear resistance of the hybrid coating are attributed to microstructural changes and the generation of new phases. The values of [Formula: see text], [Formula: see text], and [Formula: see text] are used to develop the mechanistic understanding of coatings’ erosion behavior. Splat cracking and splat detachment are the observed erosion wear mechanisms.
The most important point in machining processes is the productivity, achieved by cutting the highest amount of material in the shortest possible time using tools with the longest lifetime. Combining all the parameters involved in the machining process to maximize productivity is, nevertheless, a very complex task and becomes much more difficult when working at high speed machining in hardened steels. To address this concern, this research investigated the effects of high-pressure coolant (HPC) on the cutting performance of hard turned part (56 HRC) by coated carbide insert, as compared to completely dry cutting with respect to cutting temperature, cutting forces, tool wear and product quality. The results of this research work indicate that proper selection of machining condition and high pressure cooling system yields acceptable dimensional accuracy and surface quality. It also allows adequate tool life by keeping the cutting zone temperature and cutting forces at lower levels.
During manufacturing of a component, cutting, turning, grinding, and milling operations are inevitable and these operations induce surface residual stresses. In this study, it is shown that, depending on the process employed for cutting, residual stresses generated at the cut surfaces can vary widely and they can, in turn, make the cut surfaces of austenitic stainless steel (SS) prone to stress corrosion cracking (SCC). An austenitic SS 304L plate was cut using three different procesess: bandsaw cutting, cutting using the cut‐off wheel, and shearing. Surface residual stress measurement using the X‐ray diffraction (XRD) technique is carried out close to the cutting edges and on the cross‐section. SCC susceptibility studies were carried out as per ASTM G36 in 45% boiling magnesium chloride solution. Optical microscopic examination showed the presence of cracks, and confocal microscopy was used to measure the depth of cracks. The study confirmed that high tensile residual stresses present in the cut surfaces produced by cut‐off wheel and shear cutting make the surfaces susceptible to SCC while the surfaces produced by bandsaw cutting are resistant to SCC. Hence, it is shown that there is a definite risk of SCC for product forms of austenitic SS with cut surfaces produced using cutting processes that generate high tensile residual stresses stored for a long period of time in a susceptible environment. It is shown that, depending on the process employed for cutting, residual stresses generated at the cut surfaces can vary widely and they can, in turn, make the cut surfaces of austenitic SS prone to stress corrosion cracking (SCC). It is confirmed that high tensile residual stresses present in the cut surfaces produced by cut‐off wheel and shear cutting make the surfaces susceptible to SCC while surfaces produced by bandsaw cutting are resistant to SCC.
Hard machining operations are typically final manufacturing operations executed on the parts and components, and desired dimensional and surface quality is subjected to hard machining parameters and conditions. Mechanisms of hard machining in terms of chip formation, heat generation, machining forces, energy and power, tool wear, and lubricant usage are different from those of conventional machining. Therefore, it is important to understand these mechanisms of hard machining before designing a manufacturing process utilizing a hard workpiece material. When the tool wears faster, it causes surface integrity problems such as surface defects, roughness,white layer formation, and residual stresses. In order to reduce the tool wear, lubrication can be utilized. Since hard machining requires different cutting tools that can support and enhance the mechanics of the process, it is important to understand the options in terms of tool materials, coating materials and application methods, tool microgeometry, and tool wear and failure characteristics.
This paper investigates the performance of different wiper tool edge geometries in machining of AISI 4340 steel using finite element method (FEM) simulation. The cutting process is simulated with Arbitrary Lagrangian–Eulerian (ALE) approach in AdvantEdge. The purpose is to explore the effects of wiper tool geometries on cutting performance of AISI 4340 steel compare with conventional tool. We explored the cutting force, residual stress, Mises stress and distribution of temperature, and the chip shape also be examined. The simulation results suggest that wiper tools can increase cutting force and peak cutting temperature compare with experimental result, but it can reduce the temperature of distribution in the cutting edge which is beneficial to reduce the wear of tool. At the same time, the wiper tools also have a great influence on chip shape and stress.
Metal machining processes require primarily cutting tool materials with high hardness, high resistance to the abrasive wear and thermal stability. The development of cutting tool materials results in advanced tool materials such are primarily ceramics, cubic boron nitride and sintered carbides which are considered to have the ability to cut hard materials. As a finishing process, the machined surface of the final product needs to control the surface quality. The quality of machined surface can be determined by properties such as surface roughness, hardness variations, micro-structural changes, residual stresses, etc. These properties belong to the surface integrity of the work piece material. The surface integrity affects significantly the mechanical properties of the parts such as fatigue limit, stress-corrosion resistance, dimensional stability, etc. This paper presents an experimental study to analyze the evolution of residual stresses in relation to the different parameter of machining. For precision milling of hardened steel, parameters are cutting speed and feed rate with a constant depth of cut. Two different cutting tool materials were used in this study, ceramic and cubic boron nitride. The results show that residual stresses near the machined surface of hardened steel are suitable for compressive stress.
Additive manufacturing is a revolutionary frontier technology in the manufacturing industry. High-performance metal materials made by laser additive manufacturing are usually required subtractive machining to meet the assembly accuracy requirements. The stress coupling mechanism of FeCr alloy made by laser additive and milling subtractive is worthy of being studied. In present work, the impact of milling on residual stress of laser additive layer was investigated through experiments. The coupling interaction mechanism of laser additive stress and milling subtractive stress was analyzed. The key findings of this study are: (a) milling can change the near surface residual stress distribution of FeCr alloy made by laser additive manufacturing, resulting in a certain depth of compressive stress affected zone; (b) Mechanical load generated by milling is the main cause of compressive stress near the surface; and (c) the magnitude of compressive stress is affected by the combined effects of mechanical load and thermal load introduced by milling.
An analytical model for residual stress prediction considering the effects of material dynamic recrystallization under process-induced mechanical and thermal stresses is proposed. The effect of microstructure evolution on residual stress generation during the turning process is considered. The Johnson–Mehl–Avrami–Kolmogorov model is used to calculate grain size evolution due to thermal mechanical effects in the machining process. A modified Johnson–Cook flow stress model is developed by introducing a material grain growth–induced softening term. The classic Oxley’s cutting mechanics theories are implemented for machining forces calculation. A hybrid algorithm accounting for thermal, mechanical, and microstructure evolution effects is used to predict the residual stress profile on a machined workpiece surface. The proposed method is implemented for the orthogonal turning of Ti-6Al-4V material. Comparison is conducted between the model prediction and the literature measurement residual stress data. The general trend of the machining-induced residual stress on the machining surface is accurately captured by the proposed model. Also, the parametric study is conducted to investigate the effect of rake angle and depth of cut on the residual stress profile.
This paper reviews published literature on the manufacture and application of polycrystalline cubic boron nitride (PCBN) cutting tools. More specifically, it details the various commercial CBN products, their composition/microstructure and physical properties, together with workpiece/material applications and associated machinability data. In addition, tool wear mechanisms and component surface integrity information are reviewed. Contrasts are also made with the performance of a growing number of conventional ceramic products, including silicon nitride and whisker reinforced alumina.
Engine manufacturers generate about 50% of their total turnover with maintenance.
Damaged parts can either be replaced by spare parts or can be regenerated by e.g.
local welding processes. One major step of the process chain for regeneration is the
removal of excess weld material by cutting, which is called re-contouring. Re-contouring
is often the last process-step, which defines the final surface integrity and thus the
performance of the reparied parts.
In this work, the re-contouring process is investigated fundamentally for the titanium alloy
Ti-6Al-4V. The aim is to predict the surface integrity in order to achieve a part-individual
and effective process design within a constant high level of component quality. In this
thesis the first step was the identification of the most significant parameters, which
affect the surface integrity after re-contouring. The most significant parameter on the
formation of residual stresses is the cutting edge radius of the milling tool and the
surface topography is mainly defined by the kinematic of the cutting edge as well as its
microgeometry. These results are further used to model the surface topography and the
residual stresses by using the material removal simulation CutS.
ResearchGate has not been able to resolve any references for this publication.