Digital image correlation study on tensile properties of high strength quenched and tempered steel weld joints prepared by K-TIG and GMAW

Abstract The aim of this investigation was to compare the strength, ductility and strain distribution during tensile testing of High Hardness Armour (HHA) and Rolled Homogenous Armour (RHA) in a welded configuration, using a range of different welding procedures. Gas metal arc welding (GMAW) using austenitic filler, GMAW using ferritic filler and Keyhole-Tungsten Inert Gas (K-TIG) were investigated. The results of cross weld joint tensile tests exhibited both lower strength and lower ductility compared to the base metals. Among the three welding techniques, K-TIG resulted in the highest weld metal hardness, the highest strength and the largest ductility. GMAW using an austenitic filler resulted in the lowest strength and the smallest ductility. Digital image correlation (DIC) observation revealed strain localisation within the weld metal for specimens welded by GMAW using the austenitic filler. For specimens welded by GMAW using ferritic filler, the strain localisation occurred within the weld metal and at the interface of heat affected zone and over tempered base metal. For K-TIG welded specimens, the strain localisation was more extended to base metal. It can be concluded that among the three welding techniques used, the K-TIG resulted in the highest strength and ductility. Comparison of HHA and RHA revealed that the starting material had little influence on the tensile performance of the weld for this configuration.