Abstract
A type 329J1 duplex stainless steel was welded by gas tungsten arc welding process in argon-nitrogen gas mixture atmosphere. The microstructure, Vickers hardness and Charpy impact toughness of the weld metals were examined. The nitrogen content increased and the ferrite content decreased with an increase in the nitrogen partial pressure of atmosphere. The ferrite content decreased linearly with an increase in nitrogen content. The hardness in each of ferrite and austenite phase was nearly constant regardless of the nitrogen content of weld metal. The toughness increased with the nitrogen content at room temperature and more, while it was constant at low temperatures. The toughness of weld metal was affected by the presence of austenite and chromium nitride precipitates in ferrite. The nitrogen absorption of duplex stainless steel weld metal improved the impact toughness because of the increase in austenite content and the decrease in the amount of nitride.
