2024 年 64 巻 3 号 p. 613-618
The formation of CaS around CaO–Al2O3 in ferritic stainless steel was investigated. CaS was observed in the samples after heat treatment, although it was not detected in cast ingots. Al and S contents affect the precipitation of CaS because of the following reaction: 2[Al]+3[S]+3CaO=Al2O3+3CaS. The formation of CaS cannot be predicted by thermodynamic calculation. The growth of CaS during heat treatment is thought to be mainly controlled by S diffusion in steel. The factors for reducing CaS precipitation are discussed in this work.