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 (SIM_α′) 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 SIM_α′ content at 253 K to be higher than that at 298 K during uniform plastic deformation (UPD). Furthermore, the SIM_α′ 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 SIM_α′ 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 (SIM_ε); finally, it was SIM_α′ that pronouncedly affected the work-hardening behavior at 298 and 253 K. However, the influence of SIM_ε on the work -hardening behavior at 173 K was equivalent to that of SIM_α′ 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.

在298、253和173 K进行了超细晶粒亚稳态奥氏体不锈钢（ASS）的拉伸测试，并进行了原位高能X射线衍射（HE-XRD）。我们发现，在253 K下，奥氏体和应变诱导的α'-马氏体（SIMα _'）的面间弹性相容性优于其他温度。进一步检测到，在均匀塑性变形（UPD）期间，所有研究的奥氏体平面的马氏体相变导致253 K处的SIMα _'含量高于298 K处的SIMα _'含量。此外，SIMα _'173 K的转变最初很慢，但随后在UPD的早期到中期爆发性地发生。在253 K的UPD过程中，观察到奥氏体的位错密度和相干畴尺寸分别以适度的速率增加和减小。然而，在UPD中期，在173 K的奥氏体中发现了突然的位错并伴随着_SIMα'含量的快速增加。加工硬化行为最初是由奥氏体引起的，然后是由应变诱发的ε-马氏体（_SIMε）引起的。最后，它是SIM _α'在298和253 K.该pronouncedly影响加工硬化行为。然而，SIM的影响_ε的工作-hardening行为在173钾含量相当于SIM卡的UPD中晚期阶段的_α'导致在加工硬化曲线中形成两个峰。本文实际证明，通过降低温度可以显着调整超细晶粒亚稳态ASS的宏观和微观力学行为，这有助于深入了解其他亚稳态合金表现出的低温机械行为。