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Thermal properties of low-carbon constructional steel S235JR.
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This article presents the results of steel-sheet lap-joint-welding using laser beam radiation. The use of a laser beam and keyhole effect for deep material penetration in lap joint welding was presented. Thermodynamic mechanism of laser welding is related to material properties and process parameters. Estimation of welding parameters and joint prop...
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Context 1
... content and the trace amount of alloying elements reduce steel hardening, though some strengthening effect may occur via steel phase transformations. Thermo-physical properties of the material affect heat expansion and welding results ( Table 2). The S235JR steel has high thermal conductivity, with the phase transformation temperature of 725 • C for AC 1 and 863 • C for AC 2 [39,40]. ...Context 2
... content and the trace amount of alloying elements reduce steel hardening, though some strengthening effect may occur via steel phase transformations. Thermo-physical properties of the material affect heat expansion and welding results ( Table 2). The S235JR steel has high thermal conductivity, with the phase transformation temperature of 725 °C for AC1 and 863 °C for AC2 [39,40]. ...Context 3
... order to obtain more accurate and realistic results, a refinement procedure with FE size equal to 0.125 mm was performed near the weld zone (at the temperature exceeding 400 • C). Sheets of S235JR low-carbon constructional steel were selected for the simulation ( Table 2). The material multiphase library allowed the calculation of the overall thermo-mechanical joint properties. ...Context 4
... order to obtain more accurate and realistic results, a refinement procedure with FE size equal to 0.125 mm was performed near the weld zone (at the temperature exceeding 400 °C). Sheets of S235JR low-carbon constructional steel were selected for the simulation ( Table 2). The material multiphase library allowed the calculation of the overall thermo-mechanical joint properties. ...Citations
... The market demand for metal sheets and strips with a minimum number of cutting edge defects has been growing along with the increasingly more common use of laser joining technology [26][27][28][29][30][31]. Thus, coil slitting companies are nowadays frequently faced with the requirement that the edge of the cut sheet be free of strain and burrs. ...
... Setting the volume heat flux fraction to 0.9 means that there is surface heat flux in the model. The heat source model can be described by the following equation [24]: ...
This paper presents the results of research on laser lap welding technology of heterogeneous materials and a laser post-heat treatment method to enhance welding performance. The purpose of this study is to reveal the welding principle of austenitic/martensitic dissimilar stainless-steel materials (3030Cu/440C-Nb) and to further obtain welded joints with good mechanical and sealing properties. A natural-gas injector valve is taken as the study case where its valve pipe (303Cu) and valve seat (440C-Nb) are welded. Experiments and numerical simulations were conducted where the welded joints’ temperature and stress fields, microstructure, element distribution, and microhardness were studied. The results showed that the residual equivalent stresses and uneven fusion zone tend to concentrate at the joint of two materials within the welded joint. The hardness of the 303Cu side (181.8 HV) is less than the 440C-Nb side (266 HV) in the center of the welded joint. The laser post-heat treatment can reduce the residual equivalent stress in the welded joint and improve the mechanical and sealing properties. The results of the press-off force test and the helium leakage test showed that the press-off force increased from 9640 N to 10,046 N and the helium leakage rate decreased from 3.34 × 10−4 to 3.96 × 10−6.
... If the transfer is considered from a butt joint to a lap joint for comparable sheet thicknesses, the joining gap results primarily in the z-direction instead of in the x-or y-direction. The progress of the sheet displacement over time (Danielewski and Skrzypczyk, 2020) leading to the joint gap seems to be comparable to the butt joint, i.e. the methodical approach can be assumed to be applicable. The detection of false friends affected by the gap (Heller et al., 2015;Mrna and Hornik, 2016) could thus be addressed, for example. ...
Laser beam butt welding of thin sheets of high-alloy steel can be really challenging due to the formation of joint gaps, affecting weld seam quality. Industrial approaches rely on massive clamping systems to limit joint gap formation. However, those systems have to be adapted for each individually component geometry, making them very cost-intensive and leading to a limited flexibility. In contrast, jigless welding can be a high flexible alternative to substitute conventionally used clamping systems. Based on the collaboration of different actuators, motions systems or robots, the approach allows an almost free workpiece positioning. As a result, jigless welding gives the possibility for influencing the formation of the joint gap by realizing an active position control. However, the realization of an active position control requires an early and reliable error prediction to counteract the formation of joint gaps during laser beam welding. This paper proposes different approaches to predict the formation of joint gaps and gap induced weld discontinuities in terms of lack of fusion based on optical and tactile sensor data. Our approach achieves 97.4 % accuracy for video-based weld discontinuity detection and a mean absolute error of 0.02 mm to predict the formation of joint gaps based on tactile length measurements by using inductive probes.
... In this process, the laser beam penetrates the top surface of the upper flat bar and blends into the lower element. This method of joining materials is also used in the case of welding of dissimilar materials [4][5][6][7]. In recent years, the method of T. Domański, W. Piekarska, Z. Saternus, M. Kubiak 16 joining dissimilar materials has become increasingly used in many fields of the industry [8][9][10]. ...
... The smooth and stable temperature distributions both on the outer surface and within the domain demonstrate both the convergence on the non-linear aspects and the appropriate transfer of information achieved though the immersed boundaries Γ BG→PC and Γ PC→BG , whose details are depicted in Fig.27 for visualization pur-poses. The achievement of such smooth and stable results under the solid-liquid phase change effects has provided a robust validation of the Ov-IEFG technique potential in the thermal modelling of welding, since the heat released during such transition introduces one of the more complex material non-linearities to be solved in order to predict the performance of these processes under real conditions [9,65,66] . The solution obtained via the Ov-IEFG approach has been compared to a standard FEM-based solution with the mesh depicted in Fig.28, which has had to be highly refined and clustered towards the domain upper-surface to capture appropriately the moving heat source effects. ...
A novel overlapping nodes scheme developed in the framework of an improved element-free Galerkin (IEFG) formulation is introduced in order to solve the transient heat conduction problem with a moving heat source involved in arc welding processes, in an accurate and remarkably simple manner. The proposed approach consists in solving the aforementioned problem over two overlapping arrangements of nodes, which transfer temperature and heat flux information each other through properly defined immersed boundaries. A fine arragement of nodes (patch nodes) moves with the heat source over a coarse background nodes distribution, and the solution is enriched via an appropriate coupling of the temper- ature approximations computed over both arrangements. The patch nodes are conceived to achieve an accurate computation of the temperature distribution and corresponding heat fluxes in the heat source vicinity, whose effects cannot be properly captured by the coarse background arrangement. A detailed explanation concerning the appropriate coupling between the temperature fields of both the background and patch nodes, is also provided in this communication. The outcomes of this study reveal that the pro- posed Overset-IEFG (Ov-IEFG) formulation allows the achievement of very accurate, smooth and stable solutions for both temperature and heat flux fields, without the need of resorting to post-processing or additional local reconstruction techniques.
... -Study of technological conditions of laser welding, investigation of test joints properties [19][20][21][22][23][24][25][26]; -Analytical and numerical models of heat sources of laser beam and arc welding processes [19,20,22,23]; -Study of laser cladding and investigations of the coating's properties and tribological characteristics [27][28][29][30][31][32][33]; -Study and development of fusion welding processes, investigation of properties of the deposit produced under forced cooling or underwater conditions [34][35][36]; -Study of cladding, surfacing, and thermal spraying processes of wear-resistant coatings, characterization of the coatings [37][38][39]; -Study of application of local strengthening of the thin-walled structure by laser treatment [40]. ...
... -Study of technological conditions of laser welding, investigation of test joints properties [19][20][21][22][23][24][25][26]; -Analytical and numerical models of heat sources of laser beam and arc welding processes [19,20,22,23]; -Study of laser cladding and investigations of the coating's properties and tribological characteristics [27][28][29][30][31][32][33]; -Study and development of fusion welding processes, investigation of properties of the deposit produced under forced cooling or underwater conditions [34][35][36]; -Study of cladding, surfacing, and thermal spraying processes of wear-resistant coatings, characterization of the coatings [37][38][39]; -Study of application of local strengthening of the thin-walled structure by laser treatment [40]. ...
... The laser welding process was also investigated by Danielewski and Skrzypczyk [22]. They presented results of numerical and experimental analyses of the gaseous CO 2 laser welding of lap joints of low-carbon structural steel. ...
This Special Issue on Development of Laser Welding and Surface Treatment of Metals contains as many as twenty-two research articles mainly related to the application of lasers, but also on other welding processes that may be competitive to laser technologies under specific conditions. Despite the introduction of lasers for material processing in the 1960s, the continuous development of laser devices also leads to the development and expansion of laser technology applications. This Special Issue is a compendium of knowledge in the field of fusion welding, the manufacturing of surface layers and coatings with increased wear resistance and tribological characteristics, as well as corrosion resistance and the characterization of coatings and surface layers. The topics of the presented research articles include aspects related to laser welding (eight articles), especially technological conditions, the properties of different types of joints, and analytical and numerical aspects of modelling the laser heat sources. The second dominant issue concerns laser cladding and laser surface treatment of different ferrous and nonferrous metallic and composite materials (six articles). In addition, there are interesting results of the study of fusion welding under forced cooling of the deposit or underwater conditions (four articles), results on the characterization of wear resistance coating produced by different technologies that can be competitive for laser cladding (three articles), and an original study on local strengthening of the thin-walled structure by laser treatment (one article). This Special Issue provides very wide and valuable knowledge based on theoretical and empirical study in the field of laser and fusion welding, laser and related coating technologies, characterization of coatings, and wear phenomena.
... The process of welding ferritic stainless steels is more complicated because grain growth occurs very quickly during welding [10][11][12]. The coarse-grained structure in the weld zone and in the heat-affected zone of fusion welds is characterized by low toughness and tensibility, due to the absence of phase transformation [12][13][14][15]. The Schaeffler diagram [16], the WRC-1992 diagram [17], and the Balmforth diagram [18] are used to predict the weldability of stainless-steel types. ...
... The points for constructing the right branch of the FLCs were calculated according to Equation (14), as recommended by Keler and Brazier [36]: ...
The effect of laser welding on the mechanical properties and the prediction of formability for austenitic stainless steel AISI 304 and ferritic steel AISI 430 when welded by a YLS-5000 fiber laser, were studied in the paper. The microstructure of the welded joint was analyzed using light microscopy. The mechanical properties were determined by static tensile testing. The forming limit diagrams were produced from notched samples at R5, R17, and R25 mm. The hardness values of the welded joint and the base material were determined using the Vickers method. Samples made of AISI 430 showed that the formability suffered due to laser welding. Longitudinal coarse ferrite grains were observed in the microstructure of the AISI 430 weld metal. The coarse-grained structure of the welded joint and the continuous interface along the centerline caused the failure of the AISI 430 laser-welded samples at significantly lower actual stress and strain values than were required to break the base material. No significant changes in the formability were observed in the AISI 304 samples after laser welding. The growth of dendrites was observed in the microstructure of the AISI 304 welded joint in a direction towards the centerline of the welded joint. A comparison of the experimentally determined FLD0 values and the values calculated from predictive equations showed that a better agreement was achieved for uniform elongation than for the strain hardening exponent. The manufacturability and economic efficiency of selected parts of an exhaust system by hydromechanical drawing were evaluated on the basis of the process capability index Cpk.
... Laser welding is widely used in large-size constructions having innovative solutions for joining elements with complex shapes and in joint of elements made of various materials with different thermomechanical properties. The growing requirements to the quality of manufactured joints result in intensive experimental and numerical research on the laser welding process in a wide range, like the type of joints, process parameters or joined materials [1][2][3][4][5][6][7]. ...
The paper concerns the numerical analysis of the influence for three different of welding heat source inclinations on the weld pool shape and mechanical properties of the resulting joint. Numerical analysis is based on the experimental tests of single-side welding of two sheets made of X5CrNi18-10 stainless steel. The joint is made using a laser welding heat source. Experimental test was performed for one heating source inclination. As a part of the work metallographic tests are performed on which the quality of obtained joints are determined. Numerical calculations are executed in Abaqus FEA. The same geometrical model is assumed as in the experiment. Material model takes into account changing with temperature thermophysical properties of austenitic steel. Modeling of the motion of heating source is performed in additional subroutine. The welding source parameters are assumed in accordance with the welding process parameters. Numerical calculations were performed for three different inclinations of the source. One inclination is consistent with experimental studies. The performed numerical calculations allowed to determine the temperature field, shape of welding pool as well as deformations and stress state in welded joint. The obtained results are compared to results of the experiment.
... The first joint configuration assumes low-carbon S355J2 steel placed on the top, and the second configuration assumes the opposite: S355J2 steel on the bottom and 316L stainless steel on the top. The research assumed obtaining a sealed lap joint, with partial weld penetration in the bottom sheet [37,38]. Numerical simulations of laser welding were performed at a constant speed of 1 m/min and variable output power in the range of 3 to 6 kW, which increased with each subsequent step by the value of 0.5 kW until the assumed penetration was obtained. ...
... This type of laser has worse parameters than fiber or disc lasers, however, further planned research requires the use of single and twin spot optics for an extended The first joint configuration assumes low-carbon S355J2 steel placed on the top, and the second configuration assumes the opposite: S355J2 steel on the bottom and 316L stainless steel on the top. The research assumed obtaining a sealed lap joint, with partial weld penetration in the bottom sheet [37,38]. Numerical simulations of laser welding were performed at a constant speed of 1 m/min and variable output power in the range of 3 to 6 kW, which increased with each subsequent step by the value of 0.5 kW until the assumed penetration was obtained. ...
This paper presents the results of laser welding of dissimilar joints, where low-carbon and stainless steels were welded inthe lap joint configuration. Performed welding of austenitic and ferritic-pearlitic steels included a sealed joint, where only partial penetration of lower material was obtained.The authors presented acomparative study of the joints under different configurations. The welding parameters for the assumed penetration were estimated via anumericalsimulation. Moreover, a stress–strain analysis was performed based on theestablished model. Numerical analysis showed significant differences in joint properties, therefore, further study was conducted. Investigation of the fusion mechanism in the obtained joints wascarried out using electron dispersive spectroscopy (EDS) and metallurgical analysis. The study of the lap joint under different configurations showed considerable dissimilarities in stress–strain distribution and relevant differences in the fusion zone structure. The results showed advantages of using stainless steel as the upper material of a microstructure, and uniform chemical element distribution and stress analysis is considered.
... 0167-577X/Ó 2020 Elsevier B.V. All rights reserved. convection) used in the simulations were based on the same study [10] while the forming simulations then are performed using the FEM package of ABAQUS TM . A numerical and practical case study on an automobile part is performed in the next section. ...
Sheet metal components capitalizing on the advantages of laser-welded blanks (LWBs) are widely used in automotive industries. In the current study, residual stresses are estimated in a deep drawing process of LWBs both experimentally (hole drilling) and numerically (using SIMUFACT™ and ABAQUS™). This study aims at predicting residual stresses during laser welding and forming processes to improve the quality and service life of LWBs. Validating our proposed model on automobile parts presents promising results in which welding geometry and residual stress of LWBs are well estimated. These numerical and experimental stress analyses agree with a maximum error of 6%.
