Abstract The aging hardening and precipitation behavior of Fe-31.6Mn-8.8Al-1.38C austenitic cast steel under aging heat treatment were investigated by microstructures characterization and hardness tests. The as-quenched samples were aged at 550 °C, 700 °C, 800 °C and 900 °C for various time. After aging at 550 °C, the hardness exhibited a continuous increase and finally stabilized around 480 HB, meanwhile, the β-Mn phase nucleated at austenite grain boundaries without accompanied with α-precipitate, which is mainly related to the nano-sized κ′-carbides. When aging was conducted at 700 °C and 800 °C, the hardness was only stable at 320HB because of α precipitation and high temperature softening, and the β-Mn phase appeared through the decomposition of γ → α. According to the results of nano-indentation tests, the austenite matrix exhibited relatively low nano-hardness of the sample aged at 800 °C than that of 550 °C, due to the precipitation of micron-sized κ′-carbides. In addition, considering the size, morphology and distribution of κ phase after different aging treatments, four types of that were described in the present study.

中文翻译：

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Fe-31.6Mn-8.8Al-1.38C奥氏体铸钢时效硬化与析出行为

摘要 通过显微组织表征和硬度试验研究了Fe-31.6Mn-8.8Al-1.38C奥氏体铸钢时效热处理时的时效硬化和析出行为。淬火后的样品在 550 °C、700 °C、800 °C 和 900 °C 下老化不同时间。550℃时效后，硬度持续增加，最终稳定在480HB左右，同时β-Mn相在奥氏体晶界形核，不伴有α-析出物，主要与纳米级κ'有关。 -碳化物。在700℃和800℃时效时，由于α析出和高温软化，硬度仅稳定在320HB，并通过γ→α分解出现β-Mn相。根据纳米压痕测试结果，由于微米级 κ'-碳化物的沉淀，奥氏体基体在 800 °C 下时效的样品的纳米硬度低于 550 °C。此外，考虑到不同时效处理后κ相的大小、形态和分布，本研究描述了四种类型。