Thermal Mechanical Behavior and Microstructure Characteristics of As-Cast FeCrNiAl Steel

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 delta-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 delta-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. The thermal mechanical behavior and the dependent microstructure characteristics of the as-cast FeCrNiAl high-strength lightweight steel are studied, and 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, which is caused by local dynamic recrystallization in the dendrites and the neighboring interdendritic spacings.image (c) 2024 WILEY-VCH GmbH