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利用旋转弯曲疲劳试验方法,研究了渗碳钢的晶粒尺寸与其疲劳极限之间的定量关系。结果表明,晶粒尺寸越小,渗碳钢的疲劳极限越高,晶粒尺寸与疲劳极限之间存在类似Hall-Petch关系。疲劳试样断口观察发现,疲劳裂纹起源于渗碳层,并沿原奥氏体晶界扩展,细化渗碳层晶粒有利于提高疲劳裂纹扩展阻力,因此改善疲劳性能。
The quantitative relationship between the grain size of the carburized steel and the fatigue limit was studied by using rotational bending fatigue test. The results show that the smaller the grain size, the higher the fatigue limit of carburized steel, and the similar Hall-Petch relationship exists between the grain size and the fatigue limit. Fatigue specimen fracture observation found that the fatigue crack originated in the carburized layer, and along the original austenite grain boundaries, refining carburized layer grain is conducive to improving fatigue crack growth resistance, thus improving the fatigue performance.