Influence of heat input on the appearance, microstructure and microhardness of pulsed gas metal arc welded Al alloy weldment

In order to achieve high-quality welding of aluminum alloys, reasonable control of welding heat input is critical. Different combinations of welding parameters can achieve the same heat input, however, the relevant research results has not been reported. In this paper, the pulsed-gas metal arc welding (P-GMAW) of 4047 Al-Si alloy was used as the research object. Combining design of welding current, welding voltage and welding speed, three sets of welding parameters with the same heat input were obtained, and welding experiments were carried out on them. The formation, microstructure and mechanical properties of weld bead were analyzed. The results show that under the same heat input, the effect of the welding current and voltage on the weld bead is remarkable. With the increase of the two, the penetration, width and spreadability of the weld bead increased, and the low melting point precipitates became more aggregated. At the same time, the average hardness of the weld increased from 98.27 HV to 104.4 HV, i.e., 6.2%.