Substructure Evolution in Deformed Austenite of 904L Stainless Steel and Its Effect on Macro Flow Stress

doi:10.3901/JME.2022.20.260

Abstract

Abstract: To explore the nature of dynamic recrystallization behavior and its effect on flow stress, in this work, a 904L super austenitic stainless steel was employed to study the hot deformation behavior with different deformation processes and the evolution of substructures in deformed matrix and recrystallized grains. The results showed that under a certain conditions the stress- strain curve obtained during hot processing cannot reflect the dynamic recrystallization events at the microscopic scale. Based on EBSD analysis, the substructure of recrystallized grains is characterized by the misorientation angle lower than 1° and they are distributed periodically. This feature is relatively stable and does not change with the grain growth as well as straining. In contrast, the misorientation angle of substructure in deformed matrix increases obviously with straining, where the low angle boundaries with misorientation higher than 1° frequently occurs. The main distribution range of local misorientation is enlarged from 1° to 4°, which means that the geometrically necessary dislocations are notably increased in the deformed matrix. Although under any processing condition the grain boundary acts as a preferable place to nucleate a new recrystallized grain, their nucleation conditions are quite different. For totally recrystallized microstructure, a portion of grain boundary bulging is enough to promote the nucleation; while in deformed matrix, the high micro-strain is a necessity for the grain boundary assisted nucleation.

Key words: dynamic recrystallization, 904L Austenitic stainless steel, substructure, flow stress, EBSD

CLC Number:

TG146

LAN Liangyun, ZHANG Yiting, FU Yifeng, WANG Yinan. Substructure Evolution in Deformed Austenite of 904L Stainless Steel and Its Effect on Macro Flow Stress[J]. Journal of Mechanical Engineering, 2022, 58(20): 260-268.

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