氮—碳共渗钢的应变疲劳研究

Study on Strain Fatigue of the Nitrocarburizing Steel

45碳钢氮—碳共渗表面强化后的应变疲劳试验结果表明:共渗处理与基体,在整个试验应变范围内,均为大应变幅下呈循环硬化,小应变幅下呈循环软化;但在一定应变幅下,其硬化和软化程度各不相同。另外,共渗处理疲劳寿命的降低是表面强化层造成整体材料的塑性损失的结果。同时对断口和内部位错组态进行了观察分析。

In this paper, the strain fatigue of the surface hardened 45 steel by nitrocarburiaing is studied. It is shown that a nitrocarburizing specimen and non-treated specimen are cyclicaly hardened at a larger strain magnitude, and cyclicaly softened at a smaller strain magnitude in the range of the testing strain. But, the hardening or softening degree is different at a determinate strain magnitude. In addition, the fatigue life decreases after nitrocarburizing, are because the surface hardened layer leads to the plastic behavior loss of a whole material. And the observation and analysis of dislocation configuration on fracture surface and inside the material is made.