Weldability studies of high-strength low-alloy steel using austenitic fillers

Abstract

A study was undertaken to establish the weldability of high-strength low-alloy steel (0.3C-3Ni-2.5Si-0. 87Cr-0.52Mn-0.29Mo) using austenitic filler metals (309L and 18Cr-8Ni-6Mn) and the gas tungsten arc welding process with a view to securing high toughness in the weldment. Hot and cold cracking tests, carried out to study the cracking tendency in the weldment, showed that these steels are not prone to hot and cold cracking. Weld joints were characterised on the basis of transverse tensile, hardness and impacttoughness properties and microstructural studies. The joint efficiencies of 309L and 18-8-6 austenitic stainless-steel weld deposits were found to be around 72% compared to that of the base metal (with respect to UTS). However, the studies revealed that the toughness of the weld deposit is improved by a factor of nearly 1 1/2 compared to that of the base metal in the case of 309L filler wire, while with 18-8-6 filler wire the toughness of the weld deposit was lower than that of the base metal.