冲击疲劳循环形变阶段的晶界行为

研究了低碳钢在低周冲击疲劳循环变阶段的晶界行为，用扫描电子显微镜对试样表面进行了观察，结果表明晶界表出如下特征，滑移线既可连续地跨越晶界，也可受阻于晶界并形成台阶，晶界发生诸如增粗，消失等现象，伴随着形变过程，出现新的亚晶界，晶界的既阻碍滑移，又激发次滑移系开动，讨论了产生这些现象的可能机制。

BEHMIORS OF GRAIN BOUNDARIES DURING CYCLIC DEFORMATION UNDER IMPACT FATIGUE LOADING

An examination of grain boundaries behaviors of a low carbon steel during cyclic deformation under impact fatigue loading has been carried out. A slip Hopkinson bar was used for impact fatigue test and the surface evolution of the post test specimen was observed by SEM. The following characteristics of impact fatigUe grain boundaries behaviors were revealed: (1) Some new sub-grain boundaries are produced; (2) Some of grain boundaries become wide and some become fine to disappear; (3) On the one hand grain boundaries allow that slip bands run continuously across them, on the other hand grain boundaries obstruct slip bands so as to form grain boundary steps; (4) Grain boundaries also activate second slip system within a grain. The possible mechanisms of these phenomena were discussed.