To find the suitable deformation temperature range for the as‐cast Fe–5.5Cr–5.5Ni–3.0Al–0.27C high‐strength lightweight steel, the thermal mechanical behavior and the dependent microstructure characteristics are studied to investigate the high‐temperature mechanical response of the steel. In the results, it is shown that the microstructure of the steel owns a dendrite framework consisting of the martensite dendrite and the interdendritic austenite, among which precipitations of NiAl, Ni3Al, and δ‐Fe are induced by high‐temperature deformation. The flow stress dependence of deformation temperature shows two different variation tendencies, corresponding to the varied deformation mechanisms of strain‐induced precipitation of second phases and δ‐Fe nucleation, and then resulting in different variation of dislocation density. It is found that a periodical fluctuation of flow stress appears as the alternative occurrence of first rise and then drop followed by drop and rise, and the phenomenon is inferred to be caused by local dynamic recrystallization in the dendrites and the neighboring interdendritic spacings.

中文翻译：

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铸态 FeCrNiAl 钢的热力学行为和显微组织特征

为了找到铸态 Fe-5.5Cr-5.5Ni-3.0Al-0.27C 高强度轻质钢的合适变形温度范围，研究了热力学行为和相关显微组织特征，以研究其高温力学响应的钢材。结果表明，该钢的显微组织具有由马氏体枝晶和枝晶间奥氏体组成的枝晶骨架，其中NiAl、Ni3Al和δ-Fe是由高温变形诱导析出的。变形温度的流变应力依赖性表现出两种不同的变化趋势，对应于应变诱导第二相析出和δ-Fe形核的不同变形机制，进而导致位错密度的不同变化。研究发现，流变应力呈现先上升后下降，再下降再上升交替出现的周期性波动，推测这种现象是由枝晶及其相邻枝晶间距的局部动态再结晶引起的。