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Hybrid laser-metal inert gas keyhole welding of thick steel/Al butt joints
摘要： Dissimilar joining of steel/Al joints has become more and more signi?cant in industrial applications with particular weight saving interest. However, directly welding of steel/Al joints even in thin thickness is very di?cult. In the present study, the hybrid laser-metal inert gas (MIG) source focused on the steel side in keyhole mode was introduced to weld steel/Al butt joints of 6 mm in thickness. E?ects of the laser o?sets on the weld shape, interface microstructures, and ultimate tensile strength (UTS) of the steel/Al joints were investigated. Sound steel/Al butt joints were obtained by using this hybrid laser-MIG keyhole welding process. By increasing the laser o?sets from 0.6 and 0.8 mm, the welds exhibited a better shape with a smooth appearance attributable to the reduced heat input. The positions through the thickness of the steel/Al joints played an important role in the morphology and thickness of the intermetallic compound (IMC) layers at the Al/weld interface. The IMC layers had a thick irregular morphology at the upper part and the lower part, while the layers at the middle part exhibited a relatively thin and uniform morphology. With some certain welding conditions, the Al/weld interface at the lower part of the steel/Al joints transformed to a welding-brazing mode from a fusion one. The island-shape structures were formed at the Al/weld interface, and the IMC layers were composed of Fe2Al5 layer and needlelike Fe4Al13 phases. The maximum UTS of 87.0 MPa was obtained at a laser o?set of 0.6 mm. Although the failure occurred in the IMC layers revealed a brittle fracture, the fracture morphology and locations were a mixed failure, which had a certain resistance to the crack propagation of the IMC layers.
关键词： laser-metal inert gas welding,ultimate tensile strength,keyhole welding,intermetallic compound,steel/Al joints
更新于2025-11-28 14:24:20
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Magnetic-Field-Induced Partial-to-Full Penetration Evolution and Its Mechanism During Laser Welding
摘要： The geometry and tensile strength of magnetic-?eld-assisted laser-welded Ti-6Al-4V joints have been studied. Due to the effects of the magnetic ?eld on the melt ?ow behavior during welding, the weld penetration depth increased from 4.27 mm (partial penetration) to 5.00 mm (full penetration) and the curvature of the weld cross-section decreased, improving the weld tensile strength. The fusion zone was enlarged, showing a maximum increase of 53.4% in area when the magnetic ?eld intensity was 90 mT. The increased penetration depth and fusion zone area suggest that application of a magnetic ?eld can improve the energy utilization of the laser during laser butt welding. The mechanism of the magnetic-?eld-induced penetration depth evolution is discussed. This study provides a new energy-saving method to obtain a full-penetration weld using laser welding at lower power.
关键词： Magnetic-field-assisted laser welding,Tensile strength,Energy utilization,Ti-6Al-4V,Weld geometry
更新于2025-11-28 14:24:20
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Interface characterization and mechanical properties of dual beam laser welding-brazing Al/steel dissimilar metals
摘要： The DP590 steel to AA7075 Al-alloy with lap configuration is successfully joined by dual beam laser welding-brazing without using filler metal. Through the introduction of the derived laser beam, the wetting angle, wetting distance and the thickness of intermetallic compound (IMC) layer are well improved and controlled. It is found that the wettability of liquid Al on steel improves with the increase of laser power, i.e. the wetting angle decreasing from 25.3° to 17.8° and the wetting distance increasing from 2.17 mm to 3.19 mm as the laser power increasing from 1.0 kW to 1.6 kW. Two kinds of IMC exist at brazing interface, one is η-phase (Fe2Al5) with flatten morphology closing to the steel side and the other is θ-phase (FeAl3) with needle-like morphology adjacent to the welding-brazing seam. The thickness of IMC layer increases from 8.37 μm to 12.12 μm with increasing laser power from 1.0 kW to 1.6 kW. Tensile test shows that both the wettability and the IMC thickness have influence on the welding-brazing joint strength. Poor wettability and too thick IMC layer will result in lower strength and fracture occurred in brazing interface. The optimal joint tensile strength of 123.7 MPa on average is achieved with the laser power of 1.4 kW.
关键词： Tensile strength,Welding-brazing,IMC,Dual beam laser,Al/steel dissimilar metals
更新于2025-11-28 14:24:20
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Robust flower-like ZnO assembled ?2-PVDF/BT hybrid nanocomposite: Excellent energy harvester
摘要： Need of renewable green energy sources due to low cost synthesis, mechanically strong, high energy storage capacity with improved dielectric performance have been receiving much attention. Present work render the ZnO particle and flower-like morphology assemble semicrystalline β phase PVDF/BT nanocomposite, successfully synthesized by spin coating method and characterized by XRD, SEM, EDS and FTIR techniques. Also the energy storage density of composite with modified structure is largely increased with value 0.056 Jcm-3 at 6 MV/m which is 66% higher than virgin β-PVDF and 82% piezoelectric energy harvesting efficiency. Maximum dielectric constant is 1774 at 1 Hz for PVDF-BaTiO3-ZnOf [P-BT-ZnOf] nanocomposite film and maximum breakdown strength of 43 kVcm-1. Electrochemical study reveals that P-BT-ZnOf nanocomposite film manifest better potential material. In terms of mechanical performance, P-BT-ZnOf nanocomposite shows maximum Young modulus of 204 MPa, tensile strength of 28.7 MPa and 23.1% elongation to break. These results provide promising capability to enhance the performance of composites for energy storage application, transducers, sensors, capacitors etc.
关键词： Energy density,Tensile strength,Dielectric constant,Nanocomposites,Breakdown strength
更新于2025-09-23 15:21:01
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Modelling and optimization of process parameters to obtain maximum tensile strength for laser butt welding of 316L austenitic stainless steel sheets
摘要： The attribute of high power density but low energy-input in Laser welding offers exciting solutions to the commonly encountered disadvantages with conventional joining techniques. In this paper, 316L Austenitic Stainless Steel metal sheets were butt welded using Nd:YAG Laser welding system. Owing to its low cost and specific properties such as excellent toughness, higher creep, stress to rupture at elevated temperatures, 316L A.S.S finds wide range of applications in the industrial arena especially in the automobile and marine sectors. Hence, it becomes imperative to examine its post weld properties after performing laser welding and find optimized values of the parameters. The prominent process parameters like Laser Power, Travel speed and Focal length were analysed and optimised. Design of experiment statistical tool was embraced for the systematic conduct of the tests. Response Surface Methodology (RSM) and analysis of variance (ANOVA) techniques were employed to identify the significant process parameters affecting the weld. An empherical relationship involving the parameters was developed to predict the ultimate tensile strength. The 3D response surface plot and contour plots were generated for this model to elucidate the interaction effect of Laser parameters (Travel speed and Focal length), (Laser Power and Focal Length) & (Laser Power and Travel Speed) on Ultimate Tensile Strength. The welded specimens cut by electric discharge machining were prepared for tensile testing as per the ASTM standard. The Universal Testing Machine was used to test the welded specimen. Microhardness Testing was also carried out on the base material and the Heat Affected Zone (HAZ) using Vickers Hardness Testing machine. The tensile tested specimens were used for metallurgical analysis using Scanning Electron Microscope (S.E.M.). Specimen prepared for metallurgical analysis were sectioned, mounted, ground and polished in accordance with recommended procedures in ASTM practice E 3-11. The metallurgical observations showed the existence of undulating topography of ductile fracture surfaces. The investigations reveals that the actual values of the Ultimate tensile strength of the weld were falling close with the predicted strength obtained through the proposed model. It can be concluded that the proposed model in this work can be utilised to predict tensile strength of the weld with more precision.
关键词： Design of Experiments,Ultimate tensile strength,316 L A.S.S,Response Surface Methodology (RSM),Nd:YAG Laser welding
更新于2025-09-23 15:19:57
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Microstructure and mechanical properties of welding–brazing of Ti/Al butt joints with laser melting deposition layer additive
摘要： Laser welding–brazing of Ti/Al butt joints was performed with coaxial Al–10Si–Mg powders feeding. The experimental results indicated that a sound Ti/Al butt joint could be obtained by an additive layer approach. The influence of the laser melting deposition layers on the weld appearance, interfacial microstructure and tensile properties were investigated. High-quality joints were produced when five and seven layers were deposited. The morphology and thickness distributions of the interfacial intermetallic compounds (IMC) at the brazing interface along the thickness direction of the joint varied with the number of deposition layers. Continuous serrated IMC was obtained in joints produced by seven deposition layers, and the IMC layer was distributed homogenously along the thickness direction. The maximum thickness difference of the IMC was only approximately 0.12 μm. The microstructure of the IMC layer was composed of a nanosized granular Ti7Al5Si12 phase and serrated Ti(Al, Si)3 phase. The maximum tensile joint strength reached 240 MPa, 80% of that of the aluminum base metal, and the lower tensile strength of the other joints was caused by insufficient IMC layer or a porosity defect.
关键词： Tensile strength,Laser melting deposition,Interfacial IMC,Laser welding–brazing,Ti/Al butt joint
更新于2025-09-19 17:15:36
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Microstructural characterization and tensile behavior of Nd:YAG laser beam welded thin high strength low alloy steel sheets
摘要： Laser beam welding (LBW) has many advantages to join high strength low alloy (HSLA) steels compared with conventional fusion welding processes. The present work is focused on joining HSLA plates of 2 mm thickness efficiently through the application of Nd:YAG laser source. Only one process variable i.e. the welding speed was operated between 70 mm/s to 120 mm/s while the rest of the variables were maintained constant. The microstructure evolution of the fusion zone was recorded through optical, scanning and transmission electron microscopy. The fusion zone was observed to be wider but no major defects were present. Fusion zone experienced a change in morphology of ferrite and pearlite depending upon the rate of cooling and exposure time. Fusion zone showcased various ferrites such as acicular ferrite, widmanstatten ferrite, and grain boundary ferrite. Advancement in the welding speed helped in the formation of acicular ferrite. EBSD results presented a descending tendency of prior austenite grain size against increasing welding speed. TEM micrographs affirmed the ferrite transformation and showed the presence of dense dislocations. The changes in hardness and tensile behavior under the experimental conditions were further reported.
关键词： High strength low alloy steel,Microstructure,Tensile strength,Laser beam welding
更新于2025-09-19 17:13:59
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Optimization of Laser Sintering for Demineralized Bone/Polycaprolactone Composite Powder for Bone Tissue Scaffold
摘要： Demineralized bone matrix (DBM) is an excellent bone scaffold material, but is available in only limited sizes. An additive manufacturing (AM) method that retains these properties while enabling customized geometry fabrication would provide bone scaffolds for a larger range of geometries while maintaining the benefits of DBM. This work examines laser sintering (LS) of a blend of demineralized bone matrix (DBM) and polycaprolactone (PCL) using a CO2 laser beam. A comprehensive experimental study was carried out to find the conditions that form defect-free layers while still retaining the favorable biological features of DBM. The results identify a process setting window over which LS can be utilized to constructing complex patient-specific scaffolds. With the identified setting, first, the DBM/PCL blend was fused in the LS machine. Parts were then were further strengthened through a post-processing heat treatment. The shrinkage level, skeletal density, mechanical testing, and porosimetry of the resultant samples were compared to traditional machined DBM blocks. The maximum tensile strength of the samples and post-processing shrinkage depends on heat treatment duration. The tensile strength measurements demonstrate that the post-processing conditions can be tuned to achieve the tensile strength of the demineralized bone strips. Evaluation of the dimensional change suggests that the shrinkage along the laser paths is ~0.3% while thickness shrinks the most (up to ~20%). The porosimetry and density studies showed that the final part achieved over 40% porosity with a density comparable to blocks of DBM.
关键词： laser sintering,porosity,tensile strength,optimization,demineralized bone matrix,shrinkage,additive manufacturing,polycaprolactone
更新于2025-09-19 17:13:59
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Numerical simulation of temperature distribution and experimentation in laser beam welding of SS317L alloy
摘要： In the present study stainless steel 317L grade was chosen for joining using 400w Nd-YAG laser beam welding process. Tensile strength and temperature distribution are considered as output responses while Welding current, Frequency, Pulse width are taken as process parameters. A butt configuration of 5 mm thick plate of austenitic steel alloy and K-type digital thermocouple was used to observe the temperature experimentally. The welded plates are cut using Electro-discharge machining to prepare Tensile test specimens according to ASTME21 standard. The specimens are tested to get stress-strain graphs and ultimate tensile strengths for all the 9 cases (as per L9 Orthogonal array). Additionally, a 2D transient thermal-structural numerical simulation model was developed to simulate the complete laser welding process. The effect of each parameter has been studied experimentally and numerically. Analysis of variance (ANOVA) has been used for finding out the contribution of each input factor on the output response with the help of MINITAB software. The optimised values of process parameters are utilised to get the thermal profiles and heat-affected zone using finite element simulations. The finite element calculation of process was carried out by a parametric design language APDL available in the ANSYS finite element code. The temperature values obtained using finite element simulation and experiments are matching reasonably good with an error of 12% hence the developed simulated model can be used to study related parameters.
关键词： Tensile strength,Laser beam welding,Optimization,Simulation,FEM,Nd-YAG laser
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Ultrasonics Symposium (IUS) - Glasgow, United Kingdom (2019.10.6-2019.10.9)] 2019 IEEE International Ultrasonics Symposium (IUS) - Integrated Ultrasound and Photoacoustic Imaging for Effective Endovenous Laser Ablation: A Characterization Study
摘要： A Taguchi particle swarm optimization (TPSO) with a three-layer feedforward artificial neural network (ANN) is used to model and optimize the chemical composition of a steel bar. The novel contribution of a TPSO is the use of a Taguchi method mechanism to exploit better solutions in the search space through iterations, the use of the conventional non-linear PSO to increase convergence speed, and the use of random movement for particle diversity. The exploration and exploitation capability of the TPSO were confirmed by performance comparisons with other PSO-based algorithms in solving high-dimensional global numerical optimization problems. Experiments in this paper showed that the TPSO provides higher computational efficiency and higher robustness when solving problems involving seven non-linear benchmark functions, including three unimodal functions, one multimodal functions, two rotated functions, and one shifted functions. The results for the computational experiments show that the TPSO outperforms other PSO-based algorithms reported in the literature. Finally, the results obtained by a TPSO-based ANN model of the chemical composition of the steel bar were consistent with the actual data. That is, the proposed TPSO with three-layer feedforward ANN can be used in practical applications.
关键词： yield point,feedforward artificial neural network,tensile strength,particle swarm optimization,chemical composition of steel bar,Taguchi method
更新于2025-09-19 17:13:59