摘要
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。
Low cycle fatigue tests for different strain ranges were conducted for 316 L stainless steel at 600℃ under uniaxial loading.The results show that the dynamic strain aging（DSA） can be observed for three strain ranges.The concept of stress drop has been introduced to characterize the degree of serrated yielding for different strain ranges.The difference in the serrated yielding amount for different strain ranges can be attributed to the different interactions between solute atoms and dislocations.The maximum stress drop is related to the cyclic hardening or cyclic softening.DSA is related to the number of cycles.The material presents the obvious DSA for a few cycles and then followed by weak serrated yielding,even disappearing.However,the serrated yielding can be observed again before fatigue failure.The difference of serrated yielding can be attributed to the types of atom atmospheres at different cycles.Atype serrated wave was observed for smaller strain range,however,types of A,B,A＋B,C,and B＋C serrated wave can be found for different cycles and different phases in one cycle for larger strain range.Finally,the crack source region and crack propagation region of the fatigue fracture were observed by SEM.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2016年第7期496-502,共7页
Chinese Journal of Materials Research
基金
国家自然科学基金11102119
国家重点基础研究发展计划2011CB706504资助项目~~
