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进行了316L不锈钢在600℃不同应变条件下的单轴低周疲劳实验。结果表明,材料在三个应变范围下均表现出了动态应变时效(DSA)现象,采用“应力跌幅”的概念比较了不同应变范围的锯齿屈服程度,通过可动位错与扩散的溶质原子间不同形式的交互作用分析了此现象,讨论了最大应力跌幅的循环硬化及循环软化的相关性。DSA现象有明显的循环周次相关性,循环初期DSA现象明显,随后逐渐减弱甚至消失,但是在失效前DSA现象再次出现,气团形式的不同造成了不同循环周次下DSA现象的差异。在低应变范围DSA现象仅表现出了A型锯齿波,在高应变范围不同周次及同一周次的不同阶段波型表现为A、B、A+B、C及B+C型。最后,采用SEM分析了疲劳断口的裂纹源区和扩展区。
The uniaxial low cycle fatigue tests of 316L stainless steel under different strain at 600 ℃ were carried out. The results show that the material exhibits dynamic strain aging (DSA) at all three strain ranges. The concept of “stress drop” is used to compare the yield of sawtooth in different strain ranges. The kinematic dislocations and diffusion solutes This phenomenon was analyzed by the interaction of different forms of atoms, and the correlation between cyclic hardening and cyclic softening of maximum stress drop was discussed. The phenomenon of DSA was obviously correlated with the cycle. The phenomenon of DSA was obvious at the beginning of the cycle, and then gradually disappeared or even disappeared. However, DSA phenomenon reappeared before the failure. The difference of air mass caused the difference of DSA under different cycles. In the low strain range, the phenomenon of DSA showed only type A sawtooth waves. The waveforms showed A, B, A + B, C and B + C in different periods of high strain range and in different phases of the same cycle. Finally, the source and extension of cracks in fatigue fracture were analyzed by SEM.