부산대학교 도서관

The effect of boron addition on low cycle bending fatigue strength of carburized steel was investigated. The low-cycle bending fatigue strength of B-added steel was improved compared to SCM420. When the fatigue failure was divided into the crack initiation process and the crack propagation process, the addition of boron did not affect the crack initiation life, but improved the crack propagation life. The presence of boron in B-added steels was evaluated using TOF-SIMS and AES measurements. Grain boundary segregation of boron was not observed in the gas carburized surface layer, but precipitation of BN was observed. On the other hand, grain boundary segregation of boron was observed from the carburized surface layer toward the 400 μm core side. Therefore, it is considered that the grain boundary strengthening effect of boron was not obtained in the carburized surface layer, and the crack initiation life did not change.