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Study on the Droplet Transition Models in Laser Welding with Filler Wire
摘要： This study is intended to examine the droplet transition in the welding process. Tests were performed using a high-speed camera to assess the effect of the vertical distance between the laser–wire intersection and workpiece (H) on droplet transition. Meanwhile, forces on the droplet were analyzed to evaluate the transition model during laser welding with filler wire. The results showed transition frequency, that droplet size and forces of the model all changed with H level changing. Droplet transition and the welding process showed stability at an H level of 1 mm. Based on the liquid bridge transition model, the droplet was transferred to the molten pool in the state of balance, while the droplet entered into the molten pool under non-equilibrium state during globular transition.
关键词： Droplet transition,Laser welding with filler wire,Vertical distance between the laser–wire intersection and workpiece,Force analysis of droplet
更新于2025-09-23 15:21:01
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Porosity and joint property of laser-MIG hybrid welding joints for 304 stainless steel
摘要： Laser-metal inert gas (MIG) hybrid butt welding was carried out on 5 mm-thick 304 stainless steel to study the influence of parameters on porosity defect, weld formation, and property of the joints. Research reveals that laser-MIG hybrid welding of 304 stainless steel has porosity sensitivity. The effects of welding speed and laser power on porosity and formation of welds were analyzed. Results show that increasing of laser power and decreasing of welding speed are conducive to improve the formation of welds and reduce porosity. Improving the welding speed on the premise of ensuring proper weld formation is of considerable significance, which is recommended to be 1.8 m/min. Based on the fixed welding speed, parameter of laser power optimization is carried out. Results show that tensile strength and elongation of the welded joints reach at least 98.1% and 75.8% of the base metal when laser powers are 4.3 and 5.0 kW. Compared with real-time monitoring and the numerical simulation method, this kind of results-oriented optimization parameter method has engineering guiding significance.
关键词： property,welding parameter,weld formation,304 stainless steel,porosity,laser-MIG hybrid weld
更新于2025-09-23 15:21:01
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Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding
摘要： Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.
关键词： Pore formation,Laser powder bed fusion,X-ray imaging,Laser welding,Additive manufacturing
更新于2025-09-23 15:21:01
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Green Higha??Power Disk Lasers and Industrial Applications
摘要： In the publicly-funded ProLasKu project, the laser manufacturer Trumpf has developed a high-power laser with a wavelength of 515 nm. Substantial progress in the industrial applications of green lasers has been achieved in a cooperation between the Technical University of Munich and the companies Siemens and Continental. In addition, a camera-based system for process monitoring and quality assurance in real-time based on image processing methods has been developed.
关键词： green high-power disk lasers,industrial applications,copper,laser beam welding,process efficiency
更新于2025-09-23 15:21:01
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Comparative analysis of pulsed Nd:YAG laser welding of 304L and 904L stainless steel
摘要： The current study investigates the comparative study of similar pulsed Nd:YAG laser welding of 304L and 904L stainless steel. In the present study both austenitic stainless steel (304L) and super austenitic stainless steel (904L) are laser welded at 5 mm/s scanning speed, 25 Hz pulse frequency and 0.75 mm laser spot diameter. The ultimate tensile strength of both laser welded specimens were equal to the respective parent metals. The percent of ductility is more in 304L than 904L laser welded specimen comparatively. The weld bead shape of the two welded specimens are V shaped for 304L and H shaped for 904L at the same laser process parameters due to difference in thermophysical properties of the two materials.
关键词： 904L,Pulsed Nd:YAG,Microhardness,304L,Microstructure,Laser welding
更新于2025-09-23 15:21:01
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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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Influence of Plasma Transfer Arc Cladding of NiCrBFe filler powder on microstructure and tensile properties of Titanium Grade 2 and Ti 6Al-4V alloy dissimilar joint prepared by laser beam welding
摘要： The present investigation deals with the effect of Plasma Transfer Arc Cladding (PTAC) of 60%Ni30%CrB10%Fe filler powder on microstructure and tensile properties of Titanium Grade 2 and Ti 6Al-4V alloy dissimilar joint done by laser beam welding. In laser beam welding, full depth of penetration was achieved using the laser beam power of 1300 W, welding speed of 200 mm/min and focus distance of 10 mm. Tensile studies showed that all the failures occurred in the fusion zones of as-welded, dissimilar weldments and PTAC coated samples. Failure analysis was performed using Comsol software and the results were obsersed as well-in accordance with the experimental results. Finite element studies showed the better accuracy results while comparing both experie-mental and simulation results. The microstructure and mechanical properties studies were conducted on as-welded, dissimilar weldments and PTAC coated samples by scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectrum (EDS), and X-ray diffraction (XRD) respectively. XRD displayed the slight presence of compressive residual stress in PTAC coated samples. The microstrcture studies conducted at the fusion zone revealed that more amount of coarse grain boundaries were converted into α-Fe. The avearge heat inputs (Hi) were applied in the coated samples that converted the α + β phase structure into TiNi + TiCrFe boundarys. PTAC coated samples showed the average hardness value of 313 HV and dissimilar weldments exhibited the hardness value of 290 HV. The present study concluded that the corrosion resistance of coated materials was improved owing to the better tensile and bending strength of material.
关键词： Mechanical Properties,Plasma Transfer Arc Cladding,Finite element analysis,NiCrBFe filler powder,Laser beam welding
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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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