结构钢表面疲劳损伤演化过程的显微硬度研究方法

An Approach to Investigating Evolution of Fatigue Damage on Surface of Structural Steel Based on Microhardness

通过对疲劳过程中结构钢表面显微硬度测试结果的检验，证明了不同疲劳阶段的显微硬度测试值服从正态概率分布。依据损伤力学的基本理论建立了用显微硬度定义疲劳损伤变量的概率表达式，并应用于材料表面的损伤行为研究。分析表明，材料微观性能劣化是导致材料表面萌生显微裂纹的主要原因，而在微细观尺度上材料的损伤演化将呈现出显著的不均匀性和概率统计特征。并从疲劳裂纹萌生的无损检测角度指出了显微硬度方法是一种较方便和灵敏的表面测试技术。

It is proved that the measured values of microhardness in the different stages of fatigue obey the normal probability distribution by measured results of microhardness on the surface of structural steel during fatigue. A probability expression of the fatigue damage variable is established on the basis of damage mechanics, and is applied in the investigation of fatigue damage behavior on the surface of materials. It is pointed out that the deterioration of micro properties of material results in the initiation of microcracks, and the damage evolution shows remarkable inhomogeneity and the probability characteristics on the micro scales. Finally, it is suggested that the microhardness method is a convenient and sensitive technique of surface measurement in view of nondestructive inspection of the fatigue crack initiation.