Characterization and Optimization of Nd: YAG Laser Weld Joints of Dissimilar Metals
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The welding of dissimilar metals is challenging because of differences in physical, chemical and thermomechanical properties. This paper aims to investigate the influence of process parameters on strength, microstructure and chemical composition of weld joints made of 304L stainless steel and galvanized iron sheets. An empirical relationship in terms of laser power, welding speed and pulse duration has been proposed for optimizing the weld strength using Taguchi and Response Surface Methodology. The set of experiments are conducted as per the Taguchi’s orthogonal array design matrix. The X-ray Difractometer and Scanning Electron Microscope employed to characterize the weld joint. The PANalytical X’Pert High score software is used to analyze phase contents. It is observed that laser power has more effect than pulse duration on weld strength. The optimized strength predicted from dissimilar metal weld joints by using experimental and analytical methods are close agreement with each other. The analysis of weld samples depicts the formation of vanadium and manganese nitride precipitate at the grain boundaries.Keywords:
Weldability
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Fusion welding
Brittleness
Flash welding
Cold welding
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Weld pool
Hardening (computing)
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Product with low cost, lightweight and enhanced mechanical properties were the main reasons welding dissimilar materials thrived by most of the industries. The laser welding technique which has high-energy density beam was found suitable of carrying this task. This paper attempts to investigate welding of AISI 304 stainless steel to AISI 1008 steel through Nd:YAG pulse laser method. The main objective of this study was to find out the weldability of these materials and investigate the mechanical properties of the welded butt joints. Peak power, pulse duration and weld speed combinations were carefully selected with the aims of producing weld with a good tensile strength, minimum heat affected zone (HAZ) and acceptable welding profile. Response surface methodology (RSM) approach was adopted as statistical design technique for tensile strength optimization. Statistical based mathematical model was developed to describe effects of each process parameters on the weld tensile strength and for response prediction within the parameter ranges. The microstructure of the weld and heat affected zones were observed via optical microscope. The results indicate the developed model can predict the response within ±9% of error from the actual values.
Weldability
Butt welding
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This paper focused on the welding 1.8 mm thick 6061 aluminum alloy plates in T-joint form using dual lasers that introduced by a Nd: YAG laser and a CO 2 laser with 4043 aluminum filler wire. The effects of welding parameters on the T-joint weld appearance, microstructure and the joint mechanical properties were studied systematically, The influence of welding parameters included the distance between two laser beams, welding speed, laser power and the laser beam offset toward the stringer. The weld appearance, microstructure, hardness of the joint were evaluated by optical microscope and micro-hardness test. A monotonic quasi-static tensile test was conducted by a self-made clamping device to obtain the tensile property of welded joints. At the optimized parameters, the welded T-joint showed good weld appearance without macro defects; the micro hardness of welds ranged from 75 to 85 HV 0.3 , and the tensile strength was about 254 MPa with the fracture at the heat affected zone on the stringer side.
Tensile testing
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Development of manufacturing systems are needed to invent new kind of methodology for joining process in current research and development. Spot welding technologies are widely applied in non-conventional joining process. In this investigation predicted the mechanical properties like tensile strength and Hardness. The hardness evaluated in different regions of the spot welded Stainless steel sheet and Mild steel sheet joints such as welded zone, heat affected zone and parent material subjected to different Welding Parameters. The Experimental procedures are developed by factorial design and the regression model developed from the experimental results through Response surface methodology. The variable parameters are Electrode force, Weld Current and the Weld time. The measurable parameters are Tensile strength and hardness. The optimization process is carried out by Response surface methodology and the optimized parameters are defined the quality of the welded steel joints. The optimized welded parameters are expressed the effective joining and improve the quality of the welded member. stainless steel .The phase transformation which occur during the weld thermal cycle were analyzed which shows that fusion zone exhibited a carbide precipitates with small amount of martensite the HTHAZ exhibited a martensite, the MTHAZ exhibiting the higher hardness, the LTHAZ exhibited Cr- carbide. The grain growth which occurred in FZ and HTHAZ is a major problem accompanied with fusion welding of FSSs. It shows that the peak load and energy absorption of the welds were improved as the welding current increases due to the formation of larger FZ size at higher heat input. (2) In their research, the effects of electrode force, weld nugget, and hardness of spot welded steel joints are examined based on observed values of the experiment. Mechanical properties and the microstructure of the welded joints are having significant impact on weld nudge. The significant values of difference are identified in the hardness due to the changes presence in weld nudge. The mechanical properties and the microstructure on the heat affected zone is preserve higher value compare with welded zone. (3) Weld nudges and weld time are investigated through Finite element methods by two dimensional models in resistant spot welding. This analysis defined the effect of nugget size and weld time on AISI304L stainless steel sheet.
Spot welding
Fusion welding
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Laser welding is one of the important welding processes in industries for joining similar or different metals. Demand of dissimilar metal welding has increased now a days from high performance, cost saving and efficiency point of view. Various parameters like speed, beam power, spot diameter affect the quality, strength and cost of welding process. In this paper the influence of speed, beam power and spot diameter over strength of welded specimen is studied using Taguchi orthogonal array method. Two dissimilar metals such as 61Ni-21Cr-9M o alloy and 99.3Fe-0.45M n-0.2C steel is welded using laser beam. The experiments are carried out as per Taguchi orthogonal array design matrix to predict optimum process parameters Analysis of variance (ANOVA) is carried out to determine significantly affecting parameter and the mathematical model to estimate ultimate tensile strength has been developed using Regression method. The simulation of welding process to predict temperature distribution and residual stresses is predicted.
Orthogonal array
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Characterization
Weld pool
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This paper presents an experimental investigation of laser welding low carbon galvanized steel in butt-joint configurations. The experimental work is focused on the effects of various laser welding parameters on the welds quality. The investigations are based on a structured experimental design using the Taguchi method. Welding experiments are conducted using a 3 kW Nd:YAG laser source. The selected laser welding parameters (laser power, welding speed, laser fiber diameter, gap between sheets and sheet thickness) are combined and used to evaluate the variation of four weld quality attributes (bead width, penetration depth, underfill and hardness) and to identify the possible relationship between welding parameters and weld physical and geometrical attributes. The effects of these parameters are studied using ANOVA to find their contributions to the variation of different weld characteristics. Plots of the main effects and the interaction effects are also used to understand the influence of the welding parameters. The results reveal that all welding parameters are relevant to bead width (BDW) and depth of penetration (DOP) with a relative predominance of laser power and welding speed. The effect of laser fiber diameter on penetration depth is insignificant. Typical gap-dependent weld shapes show that a small gap results in a narrower and deeper weld. Due to the standard sheared edge, an underfill between 5% and 10% occurs for no-gap experiments. The resulting hardness values are relatively similar for all the experimental tests.
Butt welding
Butt joint
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