Investigation on DDC Susceptibility of 690 Nickel-Alloy Welding Wire

690 nickel-based welding materials are widely applied on nuclear equipment manufacturing. While the nickel-based welding metal bath has the properties of high viscosity and poor fluidity, resulting in high susceptibility to welding cracking of the nickel-based weld metal, especially ductility dip cracking. As the nuclear key equipments serve in a severe condition combined with high pressure & temperature and corrosive atmosphere, the existence of micro crack would greatly affect the life expansion of the equipments. In this paper, WHS690M -alloy welding wire was developed in order to meet the requirement of CAP1400 nuclear power plant, which has good welding performance. Strain-to-fracture (STF) test based on Gleeble-3500 thermo-mechanical simulator was performed to evaluate the DDC susceptibility of Inconel 52M and WHS690M weld by different welding parameters. And combined with EBSD, the characteristics of grain orientation was also analyzed. The minimum critical strain in STF test appeared at 1050°C, and the value reached 3.2% for WHS690M while 2.1% for Inconel 52M. Furthermore, the critical strain for both WHS690M and Inconel 52M groove weld metal was about 2.0%, which was lower than cladding metal.