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The relation between magnesium evaporation and laser absorption and weld penetration in pulsed laser welding of aluminum alloys: Experimental and numerical investigations
摘要： It is observed that in laser welding of aluminum alloys, magnesium can evaporate, and the weld penetration is dependent on Mg content of the alloy and Mg loss from the weld pool. In this research, it is proposed that the presence of Mg not in the base metal alloy, but rather the presence of Mg vapor in the plasma plume over the weld pool affects the laser absorption, and it is through this phenomenon that the weld profile and penetration is affected. Numerical simulation was performed to determine the relationship between the weld profile to estimate the effective laser absorption coefficient of four Al alloys and in parallel EPMA technique was used to determine the Mg losses of the weld metals. The combined analysis of the results showed that increasing the laser pulse energy (decreasing laser pulse frequency), Mg evaporation is increased, and that, in turn, increased the effective laser absorption coefficient. However, more laser power absorption does not necessarily mean more weld penetration. Laser absorption results in weld penetration, once the threshold Mg evaporation rate of 200 × ?10 6g/cm2 is passed.
关键词： Pulsed laser welding,Effective absorption coefficient,Aluminum alloys,Evaporation,Magnesium content,Penetration depth
更新于2025-09-23 15:21:01
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EBSD characterization of the L-605 Co-based alloy welds processed by pulsed Nd:YAG laser welding
摘要： Herein, pulsed Nd:YAG laser welding of the L-605 Co-based alloy was investigated. The effect of the welding heat input (HI) on the penetration depth, microstructure, and mechanical properties of the weld metal was studied. A field emission scanning electron microscopy equipped with an electron backscatter diffraction (EBSD) detector was used to perform microstructural characterization. The results indicated that use of the HI value in the range of 48–80 J/mm could result in the formation of sound welds with full penetration depth at bead-on-plate configuration. EBSD studies revealed that when a low HI value was used to fabricate the double-welded sample, the {1 0 0} direction of austenite grains in the weld metal was parallel to the transvers and welding directions. Regarding the single-welded sample with a high HI value, the ?1 0 0? direction was strongly oriented at an angle between 40° to 50° with respect to the welding direction. Improvement in the hardness of both single-welded and double-welded samples was observed, as compared to the based metal. The results of tensile tests showed that tensile strength of the weldments was higher or almost similar to that of the base metal. Overall, the changes in the HI values had no significant effect on mechanical behavior of the weldments.
关键词： EBSD analysis,Microstructure,Laser welding,Mechanical behavior,Co-based alloy
更新于2025-09-23 15:21:01
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Numerical simulation of temperature field of B1500HS steel/Q235 laser tailored blanks by external thermal action
摘要： Taking high-strength B1500HS steel/Q235 laser tailored blanks as the research object, this paper established the finite element model of the laser welding process of high-strength B1500HS steel /Q235 laser tailored blanks based on the theoretical model of laser welding temperature field. The temperature field of laser tailored blanks was numerically simulated under the conventional condition and External Thermal Action (ETA). The thermal cycle curve of welded joints was compared and analyzed, and the influence of welding power and welding speed on the welding width was analyzed. The results show that, under ETA condition, the cooling rate of weld and heat affected zone decreases greatly, and the residence time above the phase transition temperature becomes longer. And it is conducive to the homogenization of austenite structure at high temperature and the coordination of mechanical properties of welded joints. In addition, under the same welding power, the welding width of ETA is wider than that of conventional welding, and the larger the welding speed is, the smaller the welding width is. In order to ensure the penetration of welding, the welding speed should between 2mm/s and 7mm/s.
关键词： laser welding,external thermal action,cooling rate,numerical simulation,temperature field
更新于2025-09-23 15:21:01
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Effect of Laser Positioning on the Microstructure and Properties of NiTi-Copper Dissimilar Laser Welds
摘要： Dissimilar pulsed laser welding of 400-lm NiTi and Cu wires was used to investigate the effect of laser positioning on NiTi-Cu joint performance. Laser positioning was found to have a significant role in the microstructure due to the difference in mixing patterns and composition distributions. Homogenous element distribution was observed in both the NiTi offset and the centerline joints, while complex mixing patterns were observed in the Cu offset joints. Changing the laser position resulted in a change in alloy content in the weld pool that affected the mixing patterns, and the phases that were formed in the weld zone of each sample. By moving the laser beam from NiTi toward Cu, NiTi and NiTiCu in the weld zone were replaced by pure Cu which resulted in a decreased average hardness from 512 to 158 HV. However, high hardness values were found inside the weld zone of Cu offset welds due to the presence of hard and brittle ternary intermetallic compounds. The 100-lm Cu offset joint displayed the worst mechanical response due to its inhomogeneous microstructure and the presence of cracks and pores. It was shown that positioning the laser beam on the NiTi or on the centerline resulted in a better transition in microstructure that led to acceptable mechanical properties without optimizing laser parameters or inserting any interlayers.
关键词： dissimilar welding,copper,laser welding,laser positioning,shape-memory alloys,NiTi alloy
更新于2025-09-23 15:19:57
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Fatigue behavior improvements of laser-induction hybrid welded S690QL steel plates
摘要： In this paper, the improvements of fatigue performances of S690QL steel welded by laser-induction hybrid welding (LIHW) method were performed, mainly through the infrared imaging device to obtain the weld thermal cycle, fatigue machine to test the fatigue strength and scanning electron microscope to observe the fracture morphology. In fatigue tests, tension-tension fatigue loading and stress ratio R = 0.1 was selected. The LIHW fitted S-N curves were derived. It was found that the cracks with symmetrical grooves were initiated at the weld center (WC), while the single-laser welding (SLW) fatigue samples were fractured at the WC. However, the LIHW samples were finally fractured near heat-affected zone (HAZ). The fracture morphology of fatigue samples with stress amplitude of 108 MPa and 144 MPa were further selected to analysis. Due to different degree of defects or stress concentration, and different welding heat input absorption ability and cooling rate, in sudden fracture region, SLW fatigue samples mainly contained the brittle transient failure mode, LIHW fatigue samples mainly showed a ductile failure mode. It can thus be concluded that the LIHW method could improve the fatigue performance of S690QL steel joints.
关键词： Transient failure mode,Single-laser welding,Cracks,Laser-induction hybrid welding,Fatigue strength
更新于2025-09-23 15:19:57
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Nanosecond-pulsed laser welding of metallic glass
摘要： This study explores nanosecond-pulsed (ns-pulsed) laser welding on the metallic glass (MG) ribbons of four compositions: Fe78Si9B13, Zr65Cu15Ni10Al10, La55Ni20Al25 and Ce65Al10Cu20Co5. All MGs can be welded in the air by the ns-pulsed laser, and the crystallization of the welding joints can be avoided by proper control of the laser parameters. By varying the travel speed, pulse duration and repetition frequency, the critical crystallization time of MG can be quickly detected in a high-throughput way by ns-pulsed laser welding. At the optimal processing conditions, 70–90% of the tensile strength of the parent melt-spun ribbon can be preserved in the welded MG ribbons. The mechanical strength is well linked to the pro?le of the welding joint, which suggests a simple method to evaluate the welding quality. A welding parameter map has been established based on the experiments, and it is concluded that the laser power-density per sample thickness and the interaction time are the key factors that control the crystallization and strength of the welding joints. The map is valid for a broad range of MG compositions of all sample thickness, and thus the optimal processing conditions may be extended to all MGs with equivalent glass-forming ability.
关键词： Strength,Metallic glass,Thickness,Laser welding,Welding parameter map
更新于2025-09-23 15:19:57
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Femtosecond laser-induced non-thermal welding for a single Cu nanowire glucose sensor
摘要： Copper nanowires (CuNWs) are a key building block to facilitate carrier conduction across a broad range of nanodevices. For integration into nanoscale devices, manipulation and welding of these nanowires need to be overcome. Based on high energy density laser processing investigation, we report on innovative welding of single CuNWs to a silver film using a tightly focused laser beam combined with manipulation of CuNWs through the dielectrophoresis (DEP) method. Two types of lasers, femtosecond (FS) and continuous-wave (CW), were employed to analyze, improve, and control Cu-NW melting characteristics under high energy density irradiation. The FS laser welding of CuNWs resulted in a metallic joint with a low contact resistance suitable for functional electronic nanodevices. Computational simulations using the 1-D heat diffusion equation and finite difference method (FDM) were performed to gain an insight into metal–laser interactions for high performance welded contact development. Simulation studies on lasers established contrasting melting behavior of metal under laser irradiation. The device feasibility of CuNW based welded contacts was evaluated in terms of the electrical performance of a glucose sensor. It was possible to sense glucose concentration down to 10?6 M, demonstrating a path towards integration of CuNWs into wearable, flexible nanoelectronic devices.
关键词： glucose sensor,femtosecond laser,Copper nanowires,laser welding,dielectrophoresis,nanoelectronics,continuous-wave laser
更新于2025-09-23 15:19:57
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Experimental Study of the Technology Parameters Affect in the Laser Welded Joints
摘要： The laser welding technology is improving immediately rapidly nowadays. It has many advantages again the traditional welding technologies. The heat affected zone in case of the laser welding is very thin and the penetration of the joint is depth. This high energy technology work by a focused high energy laser light accompanied by protective gases. For welding process well known the different laser devices (gas laser, solid-state laser, disc laser). The effect of the gases and the technological parameters are not well known yet. In this work, we wanted to find some relationship between the welding parameters and the joint mechanical properties. To find this relationship it was welded the joint by different technologies parameters and the samples experimented the joint mechanical properties with different parameters and controlled by the experimental way.
关键词： technology parameters,Nd:YAG laser,laser welding,joint mechanical properties,CO2 laser
更新于2025-09-23 15:19:57
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Correlation between plume fluctuation and keyhole dynamics during fiber laser keyhole welding
摘要： In order to reveal the fluctuation mechanism of the plume induced during fiber laser keyhole welding, dynamic behaviors of both the plume and the keyhole were simultaneously observed by using the multiple-imaging method. The results show that the fluctuation period of the plume was the same as that of the laser-induced vapor moving down on the keyhole front wall (KFW). The tilt angle of the plume was the largest when the laser-induced vapor was close to the orifice. As the laser-induced vapor moved toward the bottom of the KFW, the tilt angle of the plume decreased gradually. The correlation between the plume fluctuation and the dynamics of the laser-induced vapor on the KFW was not affected by parameters such as welding speed, laser power, and focal length. Further analysis shows that the periodic drilling behavior of the laser spot on the KFW is the main reason for the periodic fluctuation of the plume.
关键词： KFW,plume,fiber laser welding,laser-induced vapor,fluctuation
更新于2025-09-23 15:19:57
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Investigation on the effect of power and velocity of laser beam welding on the butt weld joint on TRIP steel
摘要： In this study, the characterization of laser weld joint on transformation-induced plasticity (TRIP) steel sheets coupled with Nd:YAG laser welding was investigated, and the influence of welding conditions like angle of weld, power of laser, and welding speed on the strength of the joint was measured. The microstructure, tensile behavior, and microhardness of TRIP laser-welded sheets were examined in detail. The power was maintained constant, i.e., 1800 W, and by relatively varying the velocity from 25 to 30 mm/s, the strength of the joint increased drastically to 11%. In contrast, by varying the power, the effect of velocity was reduced; however, the point performance was enormously stable. Finally, the microhardness behavior of the heat-affected zone and fusion zone was investigated and discussed.
关键词： butt weld joint,heat treatment,TRIP steel,Nd:YAG laser,laser welding
更新于2025-09-23 15:19:57