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Lakshminarayanan, A. K.
- Optimization of Friction Stir Welding Process Parameters to Weld Cast A356 Aluminium Alloy Taguchi's Design of Experiments Approach
Authors
1 Mechatronics Engg., Kongu Engineering College, Perundurai, Erode, IN
2 Mech.Engg., Coimbatore Institute of Technology, Coimbatore, IN
3 Centre for Materials Joining Research, Manufacturing Dept., Annamalai University, IN
Source
Indian Welding Journal, Vol 41, No 2 (2008), Pagination: 34-41Abstract
This paper presents an application of Taguchi's Design of Experiments, to identify the optimum setting of process parameters to maximize the tensile strength of friction stir welded cast A356 aluminium alloy. The quality of weldments in friction stir welding (FSW) process mainly depends on the factors such as tool rotational speed, welding speed and axial force. Taguchi's orthogonal array L27, signal to noise ratio (S/N) and Analysis of Variance (ANOVA) are used to find the optimum levels and the effect of process parameters on tensile strength. To correlate the process parameters and the measured tensile strength, a mathematical model has been developed by multiple linear regression analysis. The mathematical model is found to be very useful to predict the tensile strength of friction stir welded cast A356 aluminium alloy. The optimum conditions to get maximum tensile strength are tool rotation speed of 1000 rpm, welding speed of 75 mm/min and axial force of 5 kN.
Keywords
Friction Stir Welding, Cast Aluminium Alloy, Tensile Strength, Taguchi Design, Regression Analysis.
- Developing Empirical Relationships to Predict Diffusion Layer Thickness, Hardness and Strength of Al-Cu Dissimilar Joints
Authors
1 Centre for Material Joining & Research, Manufacturing Dept., Annamalai University, IN
2 Mech. Engg, Pondicherry Engineering College, Pondicherry, IN
Source
Indian Welding Journal, Vol 41, No 3 (2008), Pagination: 37-45Abstract
The principal difficulty when joining Aluminium (Al) and commercial grade Copper (Cu) lies in the existence of formation of oxide films and brittle intermetallics in the bond region. However, diffusion bonding can be used to join these alloys without much difficulty. Temperature, pressure and holding time are the three main variables, which govern the integrity of the diffusion bonds. The experiments were conducted based on three factors, five-levels, and central composite rotatable design with full replications technique. Empirical relationships were developed to predict diffusion layer thickness, hardness, strength of Al-Cu joints incorporating process parameters using Response Surface Methodology. The developed relationships can be effectively used to predict the bond properties at 95 % confidence level.
Keywords
Diffusion Bonding, Aluminium Alloy, Commercial Grade Copper, Lap Shear Tensile Strength, Ram Tensile Strength.- Study on Effect of Weld Cooling Rate on Fusion Zone Microstructure and Solidification Cracks in 316L Austenitic Stainless Steel
Authors
1 Department of Mechanical Engineering, SSN College of Engineering, Kalavakkam - 603 110, IN
2 Metallurgy and Materials Group, IGCAR, Kalpakkam - 603 102, IN
Source
Indian Welding Journal, Vol 52, No 1 (2019), Pagination: 56-63Abstract
A study on effect of cooling rate on mode of solidification and microstructure was carried out on austenitic stainless steel welds. A tube and plug of 316L stainless steel was joined using Gas Tungsten Arc Welding (GTAW) and laser welding processes. The welds were characterized using optical and Scanning Electron Microscope (SEM). The results indicate that cooling rate of the weld has significant effect on solidification mode, microstructure and solidification cracking. 316L weld joints prepared using GTAW process shows duplex microstructure of vermicular ferrite and austenite in the fusion zone. Whereas, the fusion zone of laser joint shows only single phase austenite microstructure. From these observations, it is clearly understood that the changes observed in the fusion zone microstructures of GTAW and laser welds are due to change in the mode of solidification as a result of change in the weld cooling rates. The predicted mode of solidification for GTA welds for 316L composition used in this study was Austenite-Ferrite (AF) and it was also confirmed through the microstructural observations. In laser joint, the weld has solidified in fully austenitic mode which deviates from the mode of solidification predicted by the conventional constitutional diagrams and hence modified weldability diagram was used. From this investigation, it was also found that the rapid solidification during laser welding is not completely partition less because segregation of sulphur was found using Scanning Electron Microscope – Energy Dispersive Spectroscope (SEM-EDS) along the dendrite boundaries of laser welds. High cooling rate during weld solidification which influences fully austenitic mode of solidification and micro segregation of impurities along the grain boundaries contribute to solidification cracking of welds in laser joints.
Keywords
Solidification Mode, Solidification Cracking, Cooling Rate, Energy Dispersive Spectroscopy, Laser Welding, Gas Tungsten Arc Welding.References
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