1995 年 13 巻 4 号 p. 590-596
The effect of tungsten on the HAZ properties in duplex stainless steel was investigated to obtain the high pitting corrosion resistant duplex stainless steel. The steels tested were the modified 25%Cr SUS329J4L duplex stainless steel with the addition of tungsten. The welded joints produced by gas tungsten arc (GTA) welding and simulated HAZ were evaluated in terms of pitting corrosion resistance, impact toughness and microstructures including analysis of precipitates. As results, the tungsten addition up to 2 mass% was effective to improve the pitting corrosion resistance without remarkable deterioration of impact toughness in the HAZ. However, the tungsten addition exceeding 3 mass% decreased the impact toughness in the HAZ as well as pitting corrosion resistance because of accelerating the precipitation of intermetallic compound during the weld thermal cycles. From these findings it was clarified the corrosion resistance of duplex stainless steel is improved in the HAZ by the alloying of proper content of tungsten as well as in the base metal.