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The phenomenon of inhomogeneous microstructure evolution and mechanical properties of rotary friction welded (RFWed) AA2024 joints was investigated. The inhomogeneity was explored by examining the mechanical properties of samples sliced from the joint into four parts along the radius (R): Center, 0.25R, 0.5R, 0.75R. The maximum tensile strength of...
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... aluminum alloy rods with dimensions of Ф25 mm × 100 mm were chosen as base material (BM). Fig. 1 shows the three-dimensional microstructure of BM. Table 1 and Table 2 present the chemical composition and mechanical properties of BM. The welding experiments were carried out by rotary friction welding machine (HSMZ-20, Harbin Welding Institute, China) with a constant rotation speed of 1500 rpm. Before welding, the faying surface of ...
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... while the grains in TMAZ-II were under compressive stress and crushed as shown in Fig. 4(c). The microstructure of BM and HAZ both were the elongated grains, thus making the boundary between HAZ and BM unclear. But there was evident hardness difference between BM and HAZ. The exact boundary was 7.5 mm away from weld interface, as presented in Fig. 12. Fig. 5 shows the detailed microstructure in different positions, from which it can be seen that the width of DRZ, TMAZ-I and TMAZ-II were different along radius. In Center position, the width of DRZ and TMAZ (TMAZ-I) are 0.20 mm and 3.0 mm, respectively, where the microstructure on RS was almost the same with that on SS. In 0.25R ...
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... of TMAZ-II. Broken grains and equiaxed grains in TMAZ-II prevented the drastic decrement of hardening capacity in 0.25R position. However, the reason for the lower hardening ability in other three positions was that the direction of distorted grain in TMAZ-I was nearly perpendicular to the rolling direction, thus reducing the tensile strength. Fig. 11(a) presents the fracture locations of the sliced samples after tensile test. In this study, nearly more than 80 percent of samples in Center, 0.25R, and 0.75R positions fractured on RS, while almost 60 percent of samples in 0.5R position failed on SS. Fig. 11(b-e) show the microstrain distribution of sliced samples in different positions ...
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... was nearly perpendicular to the rolling direction, thus reducing the tensile strength. Fig. 11(a) presents the fracture locations of the sliced samples after tensile test. In this study, nearly more than 80 percent of samples in Center, 0.25R, and 0.75R positions fractured on RS, while almost 60 percent of samples in 0.5R position failed on SS. Fig. 11(b-e) show the microstrain distribution of sliced samples in different positions at the frame before fracture. The red area was the region of microstrain concentration which mainly distributed in TMAZ-I and HAZ, yet the microstrain in DRZ and TMAZ-II was relatively small. In 0.75R and 0.5R positions, microstrain concentration occurred both ...
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... HAZ, yet the microstrain in DRZ and TMAZ-II was relatively small. In 0.75R and 0.5R positions, microstrain concentration occurred both on stationary side and rotary side, and microstrain distributed on RS was higher than that on SS. However, in 0.25R and Center position, the region of microstrain concentration only appeared on RS. As shown in the Fig. 11(b-e), the samples in Center, 0.5R, and 0.75R positions fractured at the region between DRZ and TMAZ-I, while the fracture in 0.25R position initiated in the region between TMAZ-II and TMAZ-I, then propagated along TMAZ-I. Moreover, it could be found that the fracture directions of tensile samples in Center, 0.5R and 0.75R positions were ...
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... cross-sectional microhardness map of AA2024 RFWed joint is exhibited in Fig. 12. The microhardness in DRZ was obviously higher than that in other regions, and the microhardness in DRZ gradually increased along radius. As for TMAZ-I, the closer to DRZ it was, the higher microhardness was. Asymmetric distribution of microhardness along welding interface appeared on RS and SS. A wider high microhardness area in ...
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... uneven distribution of heat generation and friction pressure were the intrinsic characteristic of RFW. A schematic diagram was proposed to interpret the effect of heat generation and friction pressure on microstructure and precipitates along radius of joint, as shown in Fig. 13. The friction pressure is inversely proportional to radius and gradually decreases along radius direction, while the heat generation and linear velocity have an increasing trend along radius. Because of undergoing different thermo-mechanical coupling conditions, the properties in DRZ, TMAZ-I and TMAZ-II were different. The different ...
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... which made TMAZ-II an important transitional role between DRZ and TMAZ-I and improve the overall strength and elongation of sliced tensile samples. In 0.5R and 0.75R positions, the lower pressure, higher heat generation and faster linear velocity made it easy for gains to deform. The j m a t e r r e s t e c h n o l . 2 0 2 0;x x x(x x):xxx-xxx Fig. 13 -The relationship between thermo-mechanical coupling conditions and microstructure ...
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... Rotary Friction welding (FRW), is a well-established solidstate welding technique in which one rotating workpiece relative to another is fused under compressive axial pressure. Friction between the faying surfaces generates heat, which drives the interface to plasticize and the compressive force displaces the material in the interlocking surface which yields a flash collar [1][2][3]. A meritorious advantage of sub-melting temperature bonding is the joining of ferrous and non-ferrous material with a lack of filler metal, flux, shielding gas and shorter welding periods, allowing many different metal combinations to be bonded [4,5]. ...
... This is computed by detaching the overall variability of the S/N ratios, which is computed as the sum of the squared deviations from the total mean S/N ratio, into contributions from each of the design parameters and the error. First, the total sum of squared deviations SST from the total mean S/N ratio nm can be calculated as, SST = (ni − nm) 2 Where, ni = S/N ratio experiment. nm = total means of S/N ratio. ...
Sub-melting temperature bonding has the advantages of joining ferrous and non-ferrous material with a lack of filler metal, flux, shielding gas and shorter welding periods, allowing dissimilar welding. This research examines the impact of varying friction pressure (FRT), forging pressure (FP), and friction time (FT) on the rotary friction welding of dissimilar 6082 T6/AA2014 T6 aluminium alloy rods with a diameter of 18 mm. The parameters are optimized to enhance the tensile strength using the design of experiments technique of Taguchi L9 orthogonal analysis coupled with analysis of variance. The study examines the relationship between microstructural characteristics and mechanical properties, including tensile strength and microhardness. The friction pressure and forging pressure were the dominant factor influencing the tensile strength having joint efficiency of 89.54%. Extreme grain growth and recrystallization due to heat accumulation on the AA6082 side result in elongated grains adjacent to the interface, with the TMAZ grains of the rotating side being coarser than those of the AA2014 stationary side in the S6 specimen. Maximum tensile strength of 291 MPa and impact strength of 119 J were observed in the S6 specimen, which exhibited ductile failures with dimple structures in the fracture zone. The hardness in the weld zone was higher than the base metal indicating stronger bonding in the weld zone and weaker bonding in the TMAZ where the fracture occurred. The analysis showed that the S6 specimen with FRT of 90 MPa, FP of 100 MPa and FT of 22 s was the optimum parameter to enhance the tensile strength.
... The cross section of the AA2024 RFW joint illustrated in Fig. 6b indicates a regular curvature of the flash on both sides of the weld joint. This result is in good agreement with those published by Li et al. [31] and Rafi et al. [32]. According to Li et al. [33], the formation of such flash morphology is attributed to the fact that the temperature of the fixed part was higher than that of the rotating one, which resulted in severe plastic deformation during the forging phase. ...
... Thus, the microstructure obtained by using 10 s firtion time was more recrystallized than those obtained at less friction times. The following explanation fits this behavior: a short friction time resulted in less amount of the deformed material, when increasing the friction time, the generated heat increased According to the unequal local stress distribution described by Geng et al. [52] and Jin et al. [53], the TMAZ has been divided into two regions as illustrated in Fig. 11c: (i) TMAZ-1 close to NZ with distorted and elongated grains affected by tensile residual stresses, and (ii) TMAZ-2 far from NZ with crushed grains which was mainly affected by compressive residual stresses as reported by Li et al. [31,54]. The grains in the TMAZ rearranged themselves in a curved path according to the direction of the material flow as reported by Li et al [31,54]. ...
... The following explanation fits this behavior: a short friction time resulted in less amount of the deformed material, when increasing the friction time, the generated heat increased According to the unequal local stress distribution described by Geng et al. [52] and Jin et al. [53], the TMAZ has been divided into two regions as illustrated in Fig. 11c: (i) TMAZ-1 close to NZ with distorted and elongated grains affected by tensile residual stresses, and (ii) TMAZ-2 far from NZ with crushed grains which was mainly affected by compressive residual stresses as reported by Li et al. [31,54]. The grains in the TMAZ rearranged themselves in a curved path according to the direction of the material flow as reported by Li et al [31,54]. The HAZ was subjected to only welding thermal cycles, that resulted in a microstructure with coarse elongated grains (See Fig. 11b). ...
The present work investigates the Rotary Friction Welding (RFW) of similar AA2024 and dissimilar AA2024/TA6V RFW joints. The effect of friction time on the evolution of microstructure and mechanical properties was investigated to determine the optimal friction time. It was found that the increase of friction time from 2 s to 10 s resulted in improved gradually the mechanical properties of both AA2024/AA2024 and AA2024/TA6V RFW joints and shifted the fracture location from the central zone towards the AA2024 material for the AA2024/TA6V RFW dissimilar joint. The highest tensile strength values recorded were 272.54 MPa and 254.47 MPa for the similar AA2024/AA2024 and the dissimilar AA2024/TA6V RFW joints respectively, both were achieved at 10 s friction time. Scanning electron microscopic (SEM) examination and Energy Dispersive X-ray (EDX) analysis indicated the formation of an interdiffusion band at the interface of the dissimilar AA2024/TA6V RFW joint, consisting of Cu, Al, Ti, Mg, and V atoms. Increasing the friction time enhanced the material mixing and led to the alteration of the fracture mode.
... The entire process occurs at temperatures lower than the melting point of the used steels [7][8][9][10][11]. In this case, the metal of the contact surfaces experiences a local thermal deformation effect, during which a gradient microstructure is formed in the TMAZ [4,[7][8][9][10][11][12]. The thermal cycle created by tool rotation, friction force and forging force is a tool for controlling the microstructure of the joint and the TMAZ, and consequently the mechanical properties of the joints [6,8,10]. ...
The present investigation provides an assessment of the influence of the force parameters of rotary friction welding (RFW), namely the friction force and the forging force during welding tubular samples with a diameter of 73 mm and a wall thickness of 9 mm from Cr-Mn-Mo steel G105 according to API 5DP in connection with AISI 4340 The microstructure, microhardness, tensile mechanical properties and impact strength of welded joints after welding and after post-weld stress-relieving tempering were studied. The evolution of the microstructure was studied using optical and scanning electron microscopy. The length of microstructural features of the joint such as thermomechanically affected zone (TMAZ) and heat affected zone (HAZ) were measured. The welded joint of G105 and AISI4340 steels under the studied conditions has equal tensile strength compared to the base G105 steel, both in the initial state after welding and after post-weld tempering. It has been shown that carbide particles of various morphologies, separated during welding and subsequent tempering, play a major role in the processes of strengthening the thermomechanical affected zone (TMAZ). The tensile failure location is fixed in the G105 base steel. It has been established that welding power parameters influence the impact toughness of the steel interface zone: with an increase in welding force parameters, an increase in impact toughness and fracture ductility occurs. The highest impact strength occurs after the following welding parameters: friction force 145 kN, forging force 280 kN, rotation speed during friction 600 rpm, burn-off length 7 mm and subsequent tempering at 550oC. Fractographic studies have established that the fracture surface after this treatment consists entirely of small dimples of ductile fracture. This mode can be recommended as optimal for obtaining an equal-strength connection with high impact strength.
... Besides, Li et al. [18,19] rigorously researched the relationship between inhomogeneous microstructure, mechanical characteristics, and corrosion behavior of the AA2024 RFW joints to highlight the influence. RFW was also performed by Li et al. [20] to join the similar AA6061-T6 aluminum alloy joints in order to investigate the effect of the rotational speed on the friction behavior. ...
This paper is a study of the mechanical properties and microstructures of the similar friction weld joints (TiAl6V4 and AA2024) using a servo-controlled Rotary Friction Welding (RFW) system. The friction welding operations were performed with seven different values of the friction pressure in the range of 2–14 MPa. The temperature is recorded during friction welding tests using k-type thermocouples. Tensile tests and microhardness measurements were carried out to obtain the mechanical properties of the friction weld joints. Microstructural changes of individual zone of the friction welds were investigated using an optical microscope (OM), and the fracture surfaces were observed using a scanning electron microscope (SEM). For AA2024, the fracture occurs most frequently in the central zone, resulting in lower tensile strength values, while for TiAl6V4, the fracture is occurs outside the friction weld interface, indicating that the friction weld joint is more resistant than the base metal. Microscopic analysis of the fracture surfaces of the AA2024 samples revealed diverse morphologies, with rough cupular surfaces predominating, indicating a dominant ductile fracture mode. Similarly, TiAl6V4's friction welded specimen also exhibited cupules of various sizes across its surface, primarily associated with a ductile fracture mode. Overall, the optimal friction pressure values (respectively 8 and 10 MPa for TiAl6V4 and AA2024) correspond to the highest values of the mechanical properties.
... These studies have explored that when used of high axial pressure and rotation speed, revealing that such conditions lead to a significantly higher peripheral speed and rate of temperature increase compared to those at the center. This discrepancy makes it challenging to achieve a uniform temperature distribution and consistent microstructural formation across the weld interface, thus based on the mechanical properties of friction welded joints along the radial and axial direction were uneven [23,31], and due to irregular joint strength and microstructure along the radius direction were roughly always disregarded [32]. Therefore, the current study is to contribute for understanding the tensile joint strength with different effective diameters of Cr-Ni-Mo steel (AISI 316) during DDFW, ...
... The applied forge pressure, after stopping rotation, provides a consolidated weld joint [34]. Flash formation occurs on both the rotating and stationary sides, as revealed in Fig. 4a, with dissimilar amounts due to plastic deformation, was especially intense on rotating side related to the stationary side [31,35]. In addition, several factors affect the amount of flash, such as the mechanical [36], thermal [10], and chemical composition [9] of the base metal, as well as DDFW conditions of friction pressure [29], friction time [27], forge [2], and rotation speed [6]. Figure 4b shows a macrographic view of the welded joint with no welding defects, porosity, or macro cracks. ...
The present study aims to investigate the effect of the mechanical and metallurgical joint strength behavior of Cr-Ni-Mo steel (AISI 316) using direct drive friction welding. Experimental procedures in the study included macrostructure, microhardness, tensile test specimens with effective diameters of 4 mm, 6 mm, and 8 mm, microstructure of the fracture position, and tensile fracture morphology. The results concluded that the average microhardness values for 4 mm, 6 mm, and 8 mm diameter around the weld interface center are 298 Hv0.1, 300 Hv0.1, and 295 Hv0.1, respectively. The ultimate tensile strength ratios were of 95%, 98%, and 97% for 4 mm, 6 mm, and 8 mm, respectively, while, the ductility increased with the diameters of 41%, 50%, and 57% for 4 mm, 6 mm, and 8 mm, respectively, compared to AISI 316. The fracture position for all welded joints was in the adjacent region to the interface. The fracture surfaces had a fingerprint form and ductile mode at cleavage features. The center of the fracture revealed different forms of dimples and microcavities collected at that center.
... Instead, the fracture typically occurs in the center, which is the weakest area and represents the zone of stress concentration. These observations align with the findings reported by Li et al. [22]. ...
The objective underlined in this work is to apply the Rotary Friction Welding (RFW) process to joint similar AA2024 and TiAl6V4 welds. The experiment is conducted by varying the input parameters (rotational speed, friction pressure, and friction time) using Taguchi's L9 orthogonal array method. MINITAB software was used to plot the response chart. The output parameter considered in this approach is the Ultimate Tensile Strength (UTS) of the weld joint, where the optimum RFW condition for maximizing the UTS was determined. Besides, the most influential process parameter has been determined using statistical analysis of variance (ANOVA). Finally, the general regression equations of the UTS for both materials are formulated and confirmed by means of the experimental tests values.
... The presence of flash assists in the removal of unwanted oxide layers and other debris, resulting in a clean and seamless weld [5]. These deformation lines are the result of severe plastic deformation that occurs during rotary friction welding [31]. Figure 3 illustrates the visual view of the rotary friction-welded AA5083 H116 joint. ...
... The presence of flash assists in the removal of unwanted oxide layers and other debris, resulting in a clean and seamless weld [5]. These deformation lines are the result of severe plastic deformation that occurs during rotary friction welding [31]. ...
... During the rotary friction welding of AA5083 H116, Figure 5 illustrates the various weld zones that form along the weld interface. A detailed microstructural examination conducted across the weld interface revealed the division of the weldment into four distinct zones: (a) dynamically recrystallized zone (DRZ), (b) thermo-mechanically affected zone (TMAZ), (c) heat-affected zone (HAZ), and (d) base metal (BM) [31]. The DRZ exhibited fine (equiaxed) grains, characterized by an average grain size of 5 ± 2 µm, as revealed by microstructural analysis. ...
Friction welding of aluminum alloys holds immense potential for replacing riveted joints in the structural sections of the aeronautical and automotive sectors. This research aims to investigate the effects on the microstructural and mechanical properties when AA5083 H116 joints are subjected to rotary friction welding. To evaluate the quality of the welds, optical and scanning electron microanalysis techniques were utilized, revealing the formation of sound welds without porosity. The microstructural examination revealed distinct weld zones within the weldment, including the dynamically recrystallized zone (DRZ), thermo-mechanically affected zone (TMAZ), heat-affected zone (HAZ), and base metal (BM). During the friction-welding process, grain refinement occurred, leading to the development of fine equiaxed grains in the DRZ/weld zone. Tensile testing revealed that the weldment exhibited higher strength (YS: 301 ± 6 MPa; UTS: 425 ± 7 MPa) in the BM region compared to the base metal (YS: 207 ± 5 MPa; UTS: 385 ± 9 MPa). However, the weldment demonstrated slightly lower elongation (%El: 13 ± 2) compared to the base metal (%El: 15 ± 3). The decrease in ductility observed in the weldment can be attributed to the presence of distinct weld zones within the welded sample. Also, the tensile graph of the BM showed serrations throughout the curve, which is a characteristic phenomenon known as the Portevin-Le Chatelier effect (serrated yielding) in Al-Mg alloys. This effect occurs due to the influence of dynamic strain aging on the material's macroscopic plastic deformation. Fractography analysis showcased a wide range of dimple sizes, indicating a ductile fracture mode in the weldment. These findings contribute to understanding the microstructural and mechanical behavior of AA5083 H116 joints subjected to rotary friction welding.
... It is known that during friction welding of dissimilar metals, intermetallic compounds are formed at the interface, which was demonstrated in [22][23][24][25]. In friction welding of materials with the same chemical composition, the joining process ends with the formation of common grains at the interface between the parts to be welded as a result of the dynamic recrystallization process [11,26]. ...
In this work, dissimilar welded joints from AISI 1330 and AISI 4340 low-alloy carbon steels produced using rotary friction welding (RFW) are investigated. These steels are intended for the manufacture of exploration drill pipes: AISI 4340 — the tool joint and AISI 1330 — the body of the pipe. Statistical analysis based on response surface methodology (RSM), microstructural examination using scanning electron microscopy with backscattered electron diffraction (EBSD), and mechanical tests were performed to investigate the friction weld joints. Equations are derived for predicting the notch tensile strength, ultimate tensile strength, and relative elongation from RFW process parameters (heating pressure, forging pressure, rotation speed during heating, burn-off length). The results showed that the rotation speed during heating and the heating pressure to the greatest extent affect the quality of the welded joint. Parameters have been established that ensure obtaining the mechanical properties of the welded joint at the level of the base metal AISI 1330: heating pressure 60–80 MPa, forging pressure 120–140 MPa, rotation speed during heating 400 rpm, and burn-off length 4 mm. It is shown that the strength of the joint depends on the development of processes of mutual dynamic recrystallization at the steel interface and strain hardening in the thermomechanical affected zone.
... SD to DRX is responsible for the formation of peak torque in FW of pipestructure specimens. However, when it comes to the distribution of SD -DRX at the friction interface in FW, i.e., welding process of rod-structure specimens, the results are more complex due to the evolving inhomogeneous morphologies during the welding process (plasticized metal initiation and spreading) [19,26,[34][35][36][37][38]. Therefore, 'stop -action' RFW experiments were similarly conducted on rod-structure specimens according to friction torque characteristics to investigate the temporal (i. ...
Friction based joining processes are monitored and controlled according to the collectable and measurable mechanical responses, such as torque or temperature, during the process. These are a result of the underlying physical microstructural mechanism during the process, where joints are formed under shear deformation (SD) and/or dynamic recrystallization (DRX). To ensure a first quality assessment of the joints during processing, it is critical to precisely investigate the relation between (macro)-mechanical and microstructural responses (SD and DRX). In the present study, the transition from SD to DRX in friction welding has been focused and quasi in-situ observed by ‘stop - action’ rotary friction welding (RFW) experiments coupled with electron back-scattered diffraction (EBSD) analysis using pipe structures, which clarifies the characteristics of the mechanical response. Further RFW experiments with different parameters were conducted to obtain a suitable relation that correlate the DRX transition temperatures to the welding parameters. Thereafter, further ‘stop - action’ RFW experiments were performed on rod structures to investigate the spatial - temporal distribution of SD - DRX at the friction interface and accordingly the friction torque characteristics. The results show that the transition from SD to DRX takes place at the peak torque (PT) and the temperature inflection point (TIP). The TIP of pipe-structure specimens is the critical DRX temperature during FW, which is dominated by friction linear speed. The PT is the threshold that distinguishes the dominating mechanism, SD or DRX, at the welding interface when welding rod structures.
... Additionally, Li et al. [13,14] conducted extensive research on the impact of inhomogeneous microstructure, mechanical properties, and corrosion behavior on AA2024 RFW joints to emphasize their relationship. In recent years, there has been growing interest in the mechanical behavior of aluminum alloys, particularly in their cyclic behavior. ...
... The fractured Ti-6Al-4V samples exhibit a significant necking of the section, while the AA2024 alloy shows no necking since the fracture usually happens in the center that is the weakest area that represents the zone of stress concentration. These results are consistent with the findings of Li et al. [14]. The observation regarding the fractures of the Ti-6Al-4V tensile samples draws attention to the fact that fractures occur at the HAZ for T1-T4, T6, and T7 (as shown in Figure 7(c)). ...
The aim of this work is to investigate the effect of normal pressure upon the mechanical properties and their related microstructures of the similar Ti-6Al-4V and AA2024 Rotary Friction Welding (RFW) joints. The main characteristic of this process is the use of friction to generate adequate energy and raise temperature locally in order to create favorable conditions for welding at the interface between two parts. Successful welds were produced showing, among many others, that the fracture occurres at the weld interface for the AA2024 alloy, hence its low tensile strength. However, the fracture occurres outside the weld interface for the Ti-6Al-4V alloy, which indicates that the weld joint is more resistant than the base metal. The microscopic observation of the fracture surfaces of the AA2024 samples exhibits a mixture of morphologies with a majority of rough cupular surfaces, indicating a dominant ductile fracture mode. For the Ti-6Al-4V RFW joints, cupules of different sizes are observed over the entire surface that also exhibits a ductile fracture mode.
