表面微观屈服强度与疲劳极限的关系

SURFACE YIELD STRENGTH VERSUS FATIGUE LIMIT FOR STEELS

本文利用X射线对不同碳含量钢的表面微观屈服强度进行了研究。试验结果表明,表面微观屈服强度σ_(ms)远低于整体材料的屈服限,是一个反映表面抵抗塑性变形能力大小的参量。材料光滑疲劳极限往往是由裂纹荫生所控制的,与表面抵抗塑性变形的能力有关。本试验表明不同材料的σ_(ms)与存活率为50％疲劳极限的关系为:σ_(ms)=(0.81—1.02)σ_(-1);40Cr不同热处理状态的σ_(ms)与存活率为99.9％疲劳极限的关系为:σ_(ms)=(0.98—1.10)σ_(-1)。σ_(ms)的测定要比疲劳极限σ_(-1)的测定省时得多,有可能在工程上获得应用。

The surface yield strength, σ_(ms), of different high carbon alloy steels,examined by X-ray diffraction method, is far lower than the bulk one. It will reflect the parameter for resistance to surface plastic deformation. The smooth fatigue limit,σ_(-1), of materials, which is almost controlled by the crack initiation, should be associated with the damage of accumulation and the resistance against crack initiation.Experimental results show that the relations of σ^(ms)=(0.81-1.02)σ_(-1) for 50％ survival and σ_(ms)=(0.98-1.1)σ_(-1) for 99.9％ survival are exhibited for different types of steels. It seems to be much easier to etermine the surface yield strength than the fatigue limit, and an application for engineering purposes might be available.