Effect of low heat-input double-pulse gas metal arc welding on weld formation and microstructure of 6061 aluminium alloy

Abstract

Double-pulse gas metal arc welding (DP-GMAW) is a common low-melting-point metal welding method. In this study, a low heat-input double-pulse gas metal arc welding (LHDP-GMAW) was proposed based on DP-GMAW. The welding process stability, weld bead shape, microstructure, and microhardness of 6061 aluminium alloy welding were analyzed for DP-GMAW and LHDP-GMAW with different low-frequency (3, 5 and 7 Hz). Compared with DP-GMAW, the stirring effect of alternating strong and weak pulses on the molten pool of LHDP-GMAW is enhanced and the heat input is reduced. Therefore, the LHDP-GMAW can produce more obvious fish-scale ripples, lower penetration, smaller and more uniform grains, and higher microhardness. This study provides a new solution for improving the welding quality of low-melting-point metal.

Microstructures and properties of TIG welded 5A06-Al: responses to variable Ar-He alternating supplying conditions

“…These phenomena combine to create a stirring effect in the molten pool. Scholar Yu et al [17] proposed an LHDP-GMAW method by minimising the number of weak pulses to improve the stirring effect of the molten pool. Under the impact of the violent movement of the internal fluid caused by this method, the crystal will fall off, break, and melt, which can affect the crystallisation speed and crystal structure.…”

Effect of Arc Behaviour and Metal Transfer Process on Aluminium Welds during Ultrasonic Frequency Pulsed GMAW

“…Sathishkumar et al [7,8] proposed that double-pulsed GMAW had an increased cooling rate, refined grain, better mechanical property, and element segregation was completely precluded. Yu [9] proposed a low-heat-input double-pulse GMAW, which could produce more obvious fish-scale ripples, lower penetration, smaller and more uniform grains, and higher microhardness than double-pulse GMAW. Wu [10,11] presented a double-wire GMAW system for investigating the effects of high frequency phase shift of the double pulse on metal transfer and bead formation.…”