Effect of variants of gas metal arc welding process on tensile properties of AA6061-T6 aluminium alloy joints

Abstract

This article describes the influence of gas metal arc welding (GMAW) variants on tensile properties of welded thin sheets of AA6061-T6 aluminium alloy. Single V butt joints were fabricated using the four variants of the GMAW process (constant current, pulsed current, cold metal transfer and pulsed cold metal transfer) under optimized conditions. Transverse tensile properties of the welded joints were evaluated, and a microhardness survey was done along the cross section of the joints. Higher hardness is recorded in the weld metal, i.e., 79 Hv for the pulsed cold metal transfer (PCMT) joint which is 14% higher than the continuous current GMAW joints. It is observed that a PCMT-welded joint exhibited the highest tensile strength of 227 MPa which is 16% higher than the continuous current GMAW joints. The fracture surface of the tensile specimens is highly dominated by the dimples with tearing ridges which suggests that the joints have experienced sufficient plastic deformation before failure irrespective of the welding process. The results demonstrated that the joints fabricated using the PCMT process exhibited superior tensile properties with controlled segregation of phases compared to the other variants of the GMAW process due to the pulsing effect associated with the retraction of the wire.