An Experimental Study on Mechanical Behaviour of Pulsed Current Welding on Aluminum Alloy Joints

Abstract

Aluminum alloys (Al–Si–Mg alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders. An improvised method is Pulsed current tungsten inert gas (PCTIG) welding (Developed in 1950s). The pulse current is more frequently used in manual welding because it has a lot of advantages in comparison to direct current. The main advantages are improved bead contour, greater tolerance to heat sink variations, lower heat input requirements, reduced residual stresses and distortion. In the present work to study the effect of PCTIG welding over continuous current TIG welding, work plates of 6 mm thickness have been used as the base material for preparing single pass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al–5Mg (wt%)) grade aluminum alloy The preferred welding processes of moderately high strength aluminum alloy are frequently tungsten inert gas welding (TIGW) process. Two different welding techniques are used to fabricate the joints and they are: (i) continuous current TIG welding (CCGTAW) (ii) pulse current TIG welding (PCGTAW) processes. Argon (99.99% pure) has to use as the shielding gas. This report presents the effect of pulsed current TIG welding on mechanical behavior of high strength aluminum alloy joints, and studying about the grain refinement of weld bead, conducting the mechanical tests such as tensile test, impact test, and hardness test. Pulsed current welded joints have given superior mechanical properties comparative to continue current welded joints. PCTIG welded joints given high tensile strength, hardness and impact strength values. Current pulsing leads to relatively finer structure.