关键词: 316L不锈钢, 动态应变时效, 圆路径, 应力跌幅, 位错

Abstract: Low cycle fatigue tests in different strain ranges were conducted for 316L stainless steel at 873 K under circular loading. The effects of number of cycles, strain range, and loaded state on the dynamic strain aging (DSA) are discussed. DSA is more obvious in the initial several cycles, followed by weak serrated yielding. The DSA is evident before failure in larger strain range, which can be attributed to the formation of the Snoek solute atom atmospheres. The results of the effect of strain range on DSA show that the stress drop value and the serrated yielding degree increase with the increase in strain range. The increase in serrated number in larger strain range is due to the dislocation multiplication. The thermomechanical analysis shows that the serrated yielding phenomenon is more significant due to the hold-up of vacancy diffusivity when the compression changes to unloading. Scanning electron microscope（SEM）results show that the material failures are attributed to fatigue, DSA, and oxidation in two strain ranges. Key

Key words: 316Lstainlesssteel, dynamicstrainaging, circularloading, stressdrop, dislocation