金属材料的疲劳稳定性

从能量的观点阐述了金属材料在循环变形过程中性能的变化及其微观机制。循环载荷一定时，对每一种材料在循环周次达到某一定值后都对应着一个稳定的微观结构和最稳定的能量状态。如果原始组织结构的能量较高，则循环变形过程中将会向低能结构转化，并发生循环软化；相反，则发生循环硬化，也有的材料组织结构很稳定，在一定的循环变形条件下能量状态和性能不发生明显的变化。

FATIGUE STABILITY OF METAL MATERIALS

The variation of flow behavior and microstructure of metal materials during cyclic straining was described from the point of view of energy.There are a stable microstructure and a stable energy state under constant strain cyclic condition after given cycles for the metal materials.If the energy of original microstructure is higher,it will transfer to the lower energy state during cyclic straining and cyclic softening will occur.Otherwise,it will transfer to the higher energy state and cyclic hardening will occur.For some materials the microstructure is very stable,so the mechanical behavior and energy state will not change obviously.