Showing papers by "Hiroyuki Kokawa published in 1994"

Effect of nitrogen on impact toughness of duplex stainless steel weld metal

Abstract: Summary A type 329J1 duplex stainless steel was welded by single‐pass gas tungsten arc welding in an argon‐nitrogen mixed gas atmosphere. The microstructure, Vickers hardness, and Charpy impact toughness of the weld metal were examined. The nitrogen content increases and the ferrite content decreases with increasing nitrogen partial pressure of the atmosphere. The ferrite content linearly decreases with an increasing nitrogen content. The hardness of the ferrite and austenite phases is virtually constant regardless of the weld metal nitrogen content. The toughness increases with the nitrogen content at room temperature and above, remaining constant at lower temperatures. The weld metal toughness is affected by the presence of austenite and chromium nitride precipitates in the ferrite. The nitrogen absorption of duplex stainless steel weld metal improves the impact toughness through an increase in the austenite content and a decrease in the amount of nitride.