Microstructure evolution during hot deformation of REX734 austenitic stainless steel

Kulakov, Mykola and Huang, Jianglin and Ntovas, Michail and Moturu, Shanmukha (2020) Microstructure evolution during hot deformation of REX734 austenitic stainless steel. Metallurgical and Materials Transactions A, 51 (2). pp. 845-854. ISSN 1073-5623 (https://doi.org/10.1007/s11661-019-05558-6)

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Mechanical properties of a REX734 austenitic stainless steel were examined through compression testing over a wide range of temperatures (1173 to 1373 K (900 to 1100 °C)) and strain rates (0.1 to 40 s-1) that cover deformation conditions encountered in different metalworking processes. The evolution of microstructure was studied using electron microscopy combined with electron backscatter diffraction and energy dispersive spectroscopy. Partially recrystallized microstructures were obtained after compression testing at 1173 K (900 °C), while after deformation at 1273 and 1373 K (1000 and 1100 °C) the material was fully recrystallized almost in all examined cases. The role dynamic and metadynamic restoration processes in the formation of final microstructure was investigated. Σ3 twin boundaries lost their twin character and transformed into general high-angle grain boundaries as a result of deformation, while during recrystallization new Σ3 twin boundaries formed. The evolution of precipitates during compression testing and their role in the recrystallization process was also discussed.