Low temperature macro- and micro-mechanical behavior of an ultrafine-grained metastable 304 austenitic stainless steel investigated by in situ high-energy X-ray diffraction
Low temperature macro- and micro-mechanical behavior of an ultrafine-grained metastable 304 austenitic stainless steel investigated by in situ high-energy X-ray diffraction
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DOI：
10.1016/j.msea.2021.141295
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发表时间：
2021-04
期刊：
影响因子：
6.4
通讯作者：
Chengsi Zheng;Qiannan Zhen;Yongqiang Wang;Na Li
中科院分区：
文献类型：
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作者：
Chengsi Zheng;Qiannan Zhen;Yongqiang Wang;Na Li
在298、253和173 K下对超细晶亚稳奥氏体不锈钢（ASS）进行了拉伸试验，并进行了原位高能X射线衍射（HE-XRD）分析。结果表明，在253 K时，奥氏体和应变诱发α′马氏体（SIMα′）的面间弹性协调性较好。均匀塑性变形（UPD）过程中，所有奥氏体晶面的马氏体相变导致253 K下的SIMα′含量高于298 K下的SIM α ′含量。173 K时SIMα′相变开始缓慢，但在UPD早中期发生爆发性转变。在253 K下的UPD过程中，奥氏体中位错密度和共格畴尺寸分别以中等速率增加和减小;而在173 K下的UPD中期，奥氏体中出现位错突变，并伴随着SIMα′含量的快速增加。在298和253 K下，形变诱发ε马氏体（SIMε）和形变诱发α′对合金的加工硬化行为有显著影响。但在173 K下，SIMε对加工硬化行为的影响与SIMα′在UPD中后期的影响相当，导致加工硬化曲线出现双峰。本文的研究结果表明，通过降低温度可以显著地改变超细晶亚稳合金的宏观和微观力学行为，这对于深入理解其他亚稳合金的低温力学行为具有重要意义。
Tensile tests of an ultrafine-grained metastable austenitic stainless steel (ASS) were carried out at 298, 253, and 173 K along with in situ high-energy X-ray diffraction (HE-XRD). We found that the interplane elastic compatibility of austenite and strain-induced α′-martensite (SIMα′) at 253 K was better than that at other temperatures. It was further detected that the martensitic transformation of all the studied austenite planes caused the SIMα′content at 253 K to be higher than that at 298 K during uniform plastic deformation (UPD). Furthermore, the SIMα′transformation at 173 K was slow initially, but then occurred explosively during the early-middle UPD stage. The dislocation density and the coherent domain size of austenite were observed to increase and decrease at a moderate rate during UPD at 253 K, respectively; however, abrupt dislocations accompanied with the rapid increase in SIMα′content were evidenced in austenite at 173 K during the middle UPD stage. The work-hardening behavior was initially induced by austenite, and then by the strain-induced ε-martensite (SIMε); finally, it was SIMα′that pronouncedly affected the work-hardening behavior at 298 and 253 K. However, the influence of SIMεon the work -hardening behavior at 173 K was equivalent to that of SIMα′during the middle-late UPD stage, which resulted in the formation of two peaks in the work-hardening curve. This paper practically demonstrates that the macro- and micro-mechanical behaviors of an ultrafine-grained metastable ASS can be significantly tailored by reducing temperature, which is beneficial for an in-depth understanding of the low temperature mechanical behavior exhibited by other metastable alloys.