Optimization of Pulsed Current TIG Welding Parameters on Al-SiC Metal Matrix Composite - An Empirical Approach

Joining of aluminium alloys and aluminium composites are done using TIG welding, due to its economic and good quality welds among arc welding processes. During TIG welding of aluminium alloys&aluminium composites coarse grain structure formation and intermetallic formation in weld zone will result in poor mechanical properties such as reduced strength of the weld. These problems can be rectified by using the optimized pulsed current parameter of pulsed current TIG welding. Pulsed current TIG welding parameters have greater influence on weld zone and heat affected zone's microstructure&mechanical properties. To optimize the pulsed current TIG welding parameters such as peak current, base current, pulse on time and pulse frequency experiment is designed using Taguchi L₉ orthogonal array technique. From the experiment, effect of pulsed current parameters peak current, base current, pulse on time and pulse frequency on weld centre micro hardness was evaluated. Regression equation was developed using Design Expert ® statistical software to predict the weld centre micro hardness. Correlation co-efficient (r²) showed 0.99 and error % showed less than 1% which means the regression equation developed was more consistent. Empirical model was developed to optimize the pulsed current parameters of PCTIG welding was also performed using Design Expert ® statistical software. Optimized values for pulse on time, pulse frequency, peak current and base current were 54.79%, 5.12Hz, 160A and 60A respectively. Optimized predicted value of weld centre micro hardness has been observed as 77 HV. Trial runs were performed for optimized PCTIG welding condition to check the consistency of the model, which resulted only 5% of deviation between experimental values and predicted values. This showed optimized pulsed current parameters of PCTIG welding resulted in higher micro hardness which implies that strength of the weld is increased.