Influence Of Process Parameters In Friction Stir Welding of Magnesium Alloys A Quantitative Research

Abstract

This investigation details about the weld ability characteristics of Mg alloys AZ31B and AZ91B. The alloys were Friction Stir welded by following Taguchi s and#119871;9 orthogonal array with three parameters and three levels. Tool rotational speed, Welding speed and tool tilt angle were chosen as the input parameters. Super High Speed Steel was selected as the tool for welding. The alloys were joined in three sets namely AZ31B similar welds, AZ91B similar welds and AZ31B-AZ91B dissimilar welds. The surface temperature during welding was measured using a K-type contact thermocouple probe. The weld characterization was carried out through dye penetrant test, tensile test, micro hardness test and metallurgical analysis. The joint strength and hardness was compared with the base material value and the joint which produced highest strength was chosen for metallurgical analysis which comprises of macrostructure analysis, microstructure analysis and scanning electron microscopic analysis. The results obtained from thermocouple probe has been used for predicting the inside temperature through ANSYS software. This temperature was correlated with the weld characterization results. The weld process parameters has been optimized using Grey Relational Analysis (GRA) coupled with Taguchi technique. Ultimate Tensile Strength (UTS) and micro hardness were the response parameters. The optimization results were validated through confirmatory tests. The response parameters for dissimilar welds has been predicted using Artificial Neural Network (ANN). Multi-layered feed forward neural network was used for prediction. Levenberg-Marquardt back Propagation algorithm was employed for training the network. The reliability of selected model is validated through confirmatory experiments. The corrosion characteristics of the welds and base materials was tested through salt spray corrosion test.The weight loss after 24 hours and 48 hours of exposure was measured. The thermal stability of the welds was calculated using Thermo Gravimetric Analysis (TGA