Characterization of weld joints produced by continuous wave and double pulse gas metal arc welding in naval grade high-strength low-alloy steel

Abstract

The current research examines gas metal arc welding (GMAW) joints generated in naval grade high-strength low-alloy (HSLA) steel using both continuous wave GMAW (CW-GMAW) and double pulse GMAW (DP-GMAW). The joint was created in four passes with DP-GMAW, whereas CW-GMAW required eight passes. Weld joints were characterized using various techniques, including optical microscopy (OM), scanning electron microscopy (SEM), residual stress analysis, and mechanical evaluation. The mechanical evaluation consisted of microhardness, impact, and tensile tests. The Charpy V-notch (CVN) impact test was performed at room temperature and −60°C. For both CW-GMAW and DP-GMAW, the heat-affected zone and the fusion zone were harder than the base metal. The fracture occurred in the base metal region in all the tensile test specimens containing the weld joints. The DP-GMAW joints showed higher impact toughness at both room temperature and −60°C. In comparison to the fusion zone of the CW-GMAW joint, the fusion zone of the DP-GMAW joint had a greater volume fraction of acicular ferrite, a finer grain size, and a higher percentage of high-angle grain boundaries. These factors have contributed, it is believed, to the higher impact toughness of the DP-GMAW joint.