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通过拉伸-拉伸疲劳试验观测研究了渗碳钢经淬火和回火后在裂纹萌生前的疲劳行为。实验中发现:这种钢出现表层的疲劳软化与芯部的疲劳硬化共存的现象;在圆试样的渗碳层深度附近,有着一个过渡区,它将整个横截面分为向外的疲劳软化区和向内的疲劳硬化区;随外加最大循环应力和循环次数的增加,表层的疲劳软化程度和芯部的疲劳硬化程度都增加。
The fatigue behavior of carburized steel before quenching and tempering was investigated by tensile-tension fatigue test. It is found in the experiment that this steel shows the phenomenon of fatigue softening of the surface layer and the fatigue hardening of the core coexisting. In the vicinity of the depth of the carburized layer of the round specimen, there is a transition zone which divides the entire cross section into outwards fatigue softening Zone and the inward fatigue hardening zone. With the increase of the maximum cyclic stress and the number of cycles, the degree of fatigue and softening of the surface layer and the degree of fatigue hardening of the core all increase.