采用球形压头的数值模拟表明, 当应变硬化指数n大于0.23时, 不论屈服应变σy/E为何值, 在压入过程中所有材料的压痕周围均出现凹陷; 当n小于0.23时, 随着σy/E的增大, 材料由凸起向凹陷转变; 当σy/E大于0.02时, 不论n为何值材料也都出现凹陷; 当σy/E小于0.02时, 材料出现凸起向凹陷的转变. 当比值残余压痕深度/最大压入深度(hf /hmax)小于0.76时, 材料出现凹陷, n值越大凹陷越严重; 当(hf /hmax)}>0.76, 若n<0.23材料出现由凸起向凹陷转变, 若n>0.23材料均发生凹陷. 还得到了反映凸起凹陷的表观参量c2与接触面积Am之间的函数关系, 分析了c2对压痕硬度误差的影响规律.
By the numerical simulation of spherical indenter, it was observed that for the material with strain hardening exponent n >0.23, sinking-in will happen for all values of yield strain σy/E, but when n <0.23, both pile-up and sinking-in depend on the changing of σy/E. For the material with σy/E >0.02, sinking-in was observed for all values of n during indenting, but when σy/E <0.02, both pile-up and sinkin depend on the changing of n. For the ratio of residual indentation depth and maximum indentation depth (hf /hmax)<0.76, the material shows sinking-in behavior, and the higher strain hardening exponent is, the greater sinking-in is. For hf /hmax>0.76, pile-up changes to sinking-in when n <0.23 and totally sinking-in when n >0.23. The relation between the feature of pile-up or sinking-in c2 and contact area was obtained, and the effect of c2 on error of hardness was analyzed.
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