逆转变奥氏体对超级马氏体不锈钢的韧塑性协同具有重要作用，其热稳定性和含量的调控是提高材料低温韧性的关键。本工作以0Cr16Ni5Mo1超级马氏体不锈钢为研究对象，测试了淬火+回火(QT)和淬火+临界区退火+回火(QIT)工艺处理后的室温力学性能以及-196 ℃低温冲击韧性，利用热膨胀仪研究热处理过程中的逆相变行为，利用XRD、EBSD和TEM表征显微组织，深入研究了逆转变奥氏体对低温冲击韧性的影响。结果表明，0Cr16Ni5Mo1超级马氏体不锈钢经1100 ℃淬火可以得到全马氏体组织；直接进行620 ℃回火后的QT试样在马氏体板条界面处形成体积分数为16.4%的逆转变奥氏体，经-196 ℃深冷处理后逆转变奥氏体的体积分数下降至5.0%，低温冲击韧性仅有36.4 J/cm²，表现为准解理断裂。QIT工艺热处理过程中，680 ℃临界区退火后的室温组织主要由贫Ni的回火马氏体和富Ni的新鲜马氏体组成，经后续620 ℃回火可形成体积分数为23.8%的逆转变奥氏体，与QT试样相比，室温下塑性提升了6%，而强度仅降低7%。临界区退火使得后续回火过程中形成的逆转变奥氏体内平均Ni含量提高至13% (质量分数)，具有更优异的热稳定性，经-196 ℃处理后仍有18.3% (体积分数)的逆转变奥氏体可以稳定存在。这部分逆转变奥氏体在冲击过程中会发生马氏体相变而吸收冲击能量，使经过QIT工艺处理后的0Cr16Ni5Mo1超级马氏体不锈钢在-196 ℃拥有高达115.4 J/cm²的冲击韧性，其冲击断口以韧窝为主，同时存在少许准解理形貌，呈混合断裂模式。

The reversed austenite obtained through a tempering process can effectively improve the toughness and ductility of super martensitic stainless steel (SMSS). Overcoming the trade-off between thermal stability and quantity of the reversed austenite is the key to improving the cryogenic impact toughness of SMSS. In this study, the mechanical properties at room temperature and cryogenic impact toughness at -196 ^oC of 0Cr16Ni5Mo1 SMSS after quenching and tempering (QT) were investigated, along with quenching, intercritical annealing, and tempering (QIT) processes. Reverse transformation behavior during the heat treatment was studied using a thermal dilatometer, and the microstructure evolution was characterized by XRD, EBSD, and TEM. Additionally, the effect of reversed austenite on cryogenic impact toughness was extensively analyzed. The results showed that full martensite was obtained in 0Cr16Ni5Mo1 SMSS after quenching at 1100 ^oC. The volume fraction of reversed austenite in the QT samples tempered at 620 ^oC was found to be 16.4%, which decreased to 5.0% after cryogenic treatment with liquid nitrogen, and the cryogenic impact toughness of the QT samples was obtained to be only 36.4 J/cm². The microstructure of samples after intercritical annealing at 680 ^oC mainly consisted of Ni-poor tempered martensite and Ni-rich fresh martensite. Furthermore, the volume fraction of reversed austenite in the QIT samples increased to 23.8% during the subsequent tempering process at 620 ^oC while the plasticity increased by 6% and the strength decreased by 7% at room temperature. The average Ni content of reversed austenite in the QIT samples reached 13% (mass fraction), which considerably improved the thermal stability of reversed austenite. Moreover, ~18.3% (volume fraction) reversed austenite remained stable in QIT samples at -196 ^oC, thereby substantially improving the cryogenic impact toughness to 115.4 J/cm² by absorbing the impact energy through transformation into martensite. The impact fracture of the QIT samples was dominated by dimples, but there remained a little quasicleavage morphology indicating a mixed fracture mode.