The martensite-to-austenite reversion mechanisms under continuous heating and annealing of metastable austenitic stainless steel subjected to cold swaging were studied. The reversion-temperature-time diagram was constructed using high-resolution dilatometry. The diagram revealed a sequence of martensitic and diffusional reversion and recrystallization. Martensitic and diffusional reversion might be separated by using the heating rate of >10 °C/s. The reversion started via the martensitic mechanism, and the diffusional mechanism developed during subsequent heating. However, both mechanisms enhance simultaneously during continuous heating at slow heating rates (<10 °C/s). At higher temperatures, recrystallization occurred. Post-mortem microstructure analysis has allowed classifying the reverse annealing modes into low- (500–650 °C), medium- (~700 °C), and high-temperature (~800 °C) regimes. During low-temperature annealing, the development of the phase reversion, recovery, recrystallization, and carbide precipitation was characterized by both a high amount of new austenite grains and restriction of their growth that resulted in the formation of an ultrafine grain structure with an average grain size of 100–200 nm. Medium-temperature annealing was associated with the formation of almost a fully recrystallized austenitic structure, but the lamellar regions were still detected. Austenitic grain growth and dissolution of carbide particles were enhanced during high-temperature annealing.

中文翻译：

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亚稳态奥氏体不锈钢中马氏体向奥氏体反向转变的机理

研究了亚稳奥氏体不锈钢在冷锻过程中连续加热和退火下的马氏体-奥氏体回复机理。恢复温度-时间图是使用高分辨率膨胀计构建的。该图显示了马氏体和扩散回复和再结晶的顺序。马氏体和扩散回复可通过使用> 10°C / s的加热速率来分离。回复通过马氏体机理开始，并且在随后的加热过程中形成了扩散机理。但是，在慢速加热速率（<10°C / s）的连续加热过程中，两种机制同时增强。在较高的温度下，发生重结晶。事后组织分析可以将反向退火模式分为低温（500–650°C），中（〜700°C）和高温（〜800°C）模式。在低温退火过程中，相变，恢复，重结晶和碳化物沉淀的发展以大量的新奥氏体晶粒及其生长受限为特征，这导致形成具有平均晶粒的超细晶粒组织尺寸为100–200 nm。中温退火与几乎完全重结晶的奥氏体组织的形成有关，但仍检测到层状区域。在高温退火过程中，奥氏体晶粒的生长和碳化物颗粒的溶解得到增强。碳化物析出的特征是大量的新奥氏体晶粒及其生长受限，从而形成了平均晶粒尺寸为100-200 nm的超细晶粒结构。中温退火与几乎完全重结晶的奥氏体组织的形成有关，但仍检测到层状区域。在高温退火过程中，奥氏体晶粒的生长和碳化物颗粒的溶解得到增强。碳化物析出的特征是大量的新奥氏体晶粒及其生长受限，从而形成了平均晶粒尺寸为100-200 nm的超细晶粒结构。中温退火与几乎完全重结晶的奥氏体组织的形成有关，但仍检测到层状区域。在高温退火过程中，奥氏体晶粒的生长和碳化物颗粒的溶解得到增强。