Experimental Investigation and Analysis of Immerged Friction Stir Welding of Aluminium

Abstract

Friction Stir Welding (FSW) is widely used for the welding of aluminium alloy. Welding input parameters play a very significant role in determining the quality of a weld joint. The welding parameters such as tool shoulder diameters, rotational speed, welding speed and axial force play a major role in deciding a joint strength. In present study an attempt has been made to join the AA8011 aluminium alloy by using the conventional milling machine. Non-consumable tool, made of high carbon, high chromium tool steel, H-13 have been used to fabricate the joints. Friction Stir Welding is carried out on the 4 mm thick AA8011 plate. The orthogonal array with the gray relational analysis is used to determine the optimal machining parameters with considerations of the multi performance characteristics. In the present study, nine experimental runs based on the L9 orthogonal array with four columns and nine rows is used which have three levels and four input parameters. The use of Taguchi method with the gray relational analysis can greatly simplify the optimization of process parameters for multi performance characteristics. In gray relational analysis, grey relational coefficient for different process characteristics is calculated and average of these coefficients is called gray relational grade which is used as a single response for the Taguchi's experimental plan. Results of study indicate that optimized FSW parameters found are tool shoulder diameter 14 mm, rotational speed 1400 rpm, welding speed 80 mm/min and axial force 1.5 KN.Comparison between FSW in air and immersed condition for the microstructure, tensile strength and micro hardness is carried out. Immersed FSW shows 76 percent tensile strength value compare to the base metal.