Abstract High manganese steels are promising candidates for applications in cryogenic environments. In this study, we investigate the mechanical and microstructural responses of a high manganese twinning induced plasticity (TWIP) steel at a low-temperature range (from 373 to 77 K) via in situ neutron diffraction qualification and correlative microscopy characterization. During plastic deformation, stacking fault probability and dislocation density increased at a faster rate at a lower temperature, hence, higher dislocation density and denser mechanical twins were observed, confirmed by microscopic observation. Stacking fault energy was estimated, dropping linearly from 34.8 mJm−2 at 373 K to 17.2 mJm−2 at 77 K. A small amount of austenite transferred to martensite when deforming at 77 K. The contributions to flow stress from solutes, grain boundary, dislocation, and twinning were determined at different temperatures, which shows that the high work strain hardening capacity of the TWIP steel originates from the synergetic strengthening effects of dislocations and twin-twin networks. These findings reveal the relationship among stacking fault energy, microstructure, and deformation mechanisms at the low-temperature range, paving a way in designing TWIP steels with the superb mechanical performance for cryogenic applications.

中文翻译：

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TWIP 钢在低温下的协同变形路径：原位中子衍射

摘要 高锰钢是用于低温环境的有希望的候选材料。在这项研究中，我们通过原位中子衍射鉴定和相关显微镜表征研究了低温范围（373 至 77 K）下高锰孪晶诱导塑性 (TWIP) 钢的机械和微观结构响应。在塑性变形过程中，层错概率和位错密度在较低温度下以较快的速度增加，因此观察到更高的位错密度和更密集的机械孪晶，这通过显微观察得到证实。估计堆垛层错能，从 373 K 时的 34.8 mJm-2 线性下降到 77 K 时的 17.2 mJm-2。在 77 K 变形时，少量奥氏体转移到马氏体。溶质对流动应力的贡献，在不同温度下确定了晶界、位错和孪晶，这表明 TWIP 钢的高加工应变硬化能力源于位错和孪晶网络的协同强化作用。这些发现揭示了堆垛层错能、微观结构和低温范围内的变形机制之间的关系，为设计具有出色低温应用机械性能的 TWIP 钢铺平了道路。