利用压痕硬度研究疲劳中材料表观塑性行为

Investigation of Plastic Behaviour on Surface of Structural Steel During Fatigue by Microindentation Hardness

应用显微硬度计测定了低周疲劳中正火４５＾＃钢光滑试样的表面维氏显微硬度变化规律。随循环进行，硬度均值呈现初期减少，逐渐增大及后期再次减小３个阶段，硬度方差在整个寿命域内呈现出料大离散特征。

The experimental rule of Vickers microhardness on the surface of normalized 45~# steel in a smooth sample was measured with microhardness tester during low cycle fatigue.It showed that the statisti- cal means of microhardness appeared three periods with the number of cycle,i,e.decreasing during initial stage,increasing gradually and decreasing again during later stage,and the mean square deviations of micro- hardness appeared larger scatter within the fatigue life.By analyzing the microindentation with elastic-plastic method,the changes of the cyclic plastic state and the properties of the hardening and softening of the materi- al on the surface of specimens during fatigue were studied.