|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||9th International Symposium on High Temperature Metallurgical Processing
||The Effect of Austenitizing Temperature on Hardenability, Precipitation and Mechanical Properties of Boron Bearing Cr-Mo Alloy Steel
||Yaxu Zheng, Fuming Wang, Changrong Li, Dan Wu, Xi Chen, Shuai Liu
|On-Site Speaker (Planned)
In order to improve hardenability and toughness of train axles for high-speed railway, Nb and B were added in 25CrMo alloy steel. Thermo-Calc, SEM, TEM, EDS and Jominy test were used to investigate the precipitates, microstructures and hardenability. The results show that the hardenability is deteriorated with increasing austenitizing temperature and B content. Tensile strength has little relationship with B content, but impact toughness is influenced significantly by B bearing precipitates. The excessive B atoms segregating at the PAG boundaries promote M2B precipitation not only during austenitizing to deteriorate the hardenability significantly, but also during tempering to deteriorate toughness obviously. Besides M2B precipitates, there are M23C6, M7C3 and MC carbides in tempered steel. M23C6 tends to precipitate at PAG and sub-grain boundaries, M7C3 and MC tend to precipitate in matrix. Therefore, B content in 25CrMo steel should be controlled below 20 ppm, meanwhile, the austenitizing temperature should also be optimized.