第三种应变时效与机械波谱关联性探讨

Discussion of the relevancy of the third-type strain aging and mechanical spectroscopy

为理解和揭示第三种应变时效现象,对DH36钢在拉、压加载,温度从77 K到1 000 K,应变率从0.001/s到3000/s下的塑性流动行为进行了系统研究,分析了时效发生的规律、特性以及时效发生的温度、应变率和应变的关系.同时,基于间隙原子与位错相互作用的本质,探讨了第三种应变时效现象与滞弹性材料机械波谱(即内耗峰)关联性.研究表明:金属在第三种应变时效温度区经变形后,材料的强度会提高,且材料的韧性(即断裂应变)并不变化;第三种应变时效的发生需要一定的预变形以造成大量空位,这将有益于间隙原子在位错周围的扩散形成,当温度和变形率达到某一匹配值时,在后续连续的塑性变形过程中,围绕位错的间隙原子气团连续对位错拖曳使得位错滑移阻力增加,导致第三种应变时效发生;DH36钢应变时效发生时的峰值应力温度与应变率呈现指数关系;第三种应变时效发生的温度区与金属机械波谱(内耗峰)温度区基本一致,都具有波动性,所以本质上第三种应变时效是机械波谱的另一表现形式.

To understand the third-type strain aging phenomena,the plastic flow behavior of DH36 steel is systematically studied under tensile and compression load over a temperature range from 77 K to 1000 K,and a strain-rate range from 0.001/s to 3000/s.Based on essential interaction between interstitial atoms and dislocation,the relevancy relation between the internal friction peak（or mechanical spectroscopy） in anelastic materials and the third-type strain aging phenomena are explored.The reseaches show that through pre-deformation during the third-type strain aging temperature region,the strength of metal increases and its toughness does not change.In continuous plastic deformation,the interstitial atoms atmosphere around the dislocation continually drags and increases gliding resistance to the dislocation motion,this results in the third-type strain aging phenomena.The temperature of the aging peak stress is exponential to strain rate for DH36 steel.The occurring temperature region of the third-type strain aging phenomena is basically consistent with that of mechanical spectroscopy（the internal friction peak）,essentially this aging is another mode of mechanical spectroscopy.