高硫黄含有フェライト系耐熱鋳鋼の靱性 Toughness of Ferritic Heat-Resistant Cast Steels with High Sulfur Contents
The influence of sulfur addition on the toughness of ferritic 16 mass % Cr cast steels was investigated in relation with sulfide distribution. Three types of base alloys different in solidification reaction were used and were added with up to 0.2 mass % sulfur. Although Charpy impact toughness at room temperature and transition temperature are slightly affected by sulfur addition, the intermediate temperature toughness (ITT) above the transition temperature decreases with increasing sulfur content, and degree of decrease differs among the base alloys. In the base alloy with 0.04 % C, which solidifies in α single phase, ITT is remarkably decreases by the addition of up to 0.1 mass % sulfur, because fine sulfides crystallize on the grain boundaries, resulting in embrittlement of those areas. In the base alloy with 0.2 % C and 0.7 % Nb, in which Nb carbides crystallize, ITT is also sharply reduced, because sulfides crystallize in the interdendritic regions together with Nb carbides, also resulting in embrittlement of those areas. On the other hand, in the base alloy with 0.2 % C, which solidifies through peritectic reaction (α + liquid → γ), the decrease in ITT with increasing sulfur content is small. Its ITT is highest amongst all base alloys even when the sulfur content is over 0.1 %, because large sulfides crystallize uniformly.
- 鋳造工学 = Journal of Japan Foundry Engineering Society
鋳造工学 = Journal of Japan Foundry Engineering Society 71(3), 171-176, 1999-03