Characterization of pulsed-tungsten inert gas (PTIG) welding on AA5754-H111 alloy: mechanical properties and microstructural analysis

Abstract

Aluminium and its alloys were widely used in engineering because they are lightweight, strong, and resistant to corrosion. However, using standard arc welding techniques can be difficult when dealing with such materials. Pulsed-Tungsten Inert Gas (PTIG) welding is being researched as a potential solution to this problem. This study is the first to investigate the use of the straightforward and intuitive PTIG technique on the ubiquitous AA5754 wrought aluminium alloy. Welded samples were supplied for examination of mechanical parameters such as surface hardness and strength under impact and tensile loading. The results of a statistical analysis of the mechanical characterization of a PTIG-welded permanent joint fabricated from AA5754 aluminium alloy were presented and discussed. The heat-affected zone (HAZ) on the AA5754 retracting side of the weld had a hardness of 50–70 Hv0.5, while the HAZ on the AA5756 side had a hardness of 90–100 Hv0.5, as measured by testing on the perfect weld specimen. Samples taken from different parts of the weldment all showed that the HAZ is the softest and weakest. The shattered surface of the welded sample consisted of flat facets and quasi-cleavage patterns, as revealed by scanning electron microscopy. Analysis of the HAZ microstructure revealed widespread dissolution of Mg2Si precipitates in the AA5754-H111.