Design of a hot deformation processing map for a Ni-free, N-bearing austenitic stainless steel. (June 2021)

• Record Type: Journal Article
• Authors: Khorshidi, H.; Kermanpur, A.; Rastegari, H.; Ghassemali, E.; Somani, M.C.
• Is Part Of: Materials today communications. Volume 27(2021)
• Publication Date: 2021-06
• Subjects: Hot deformation -- Ni-free austenitic stainless steel -- Processing map -- DRX -- Instability; Materials science -- Periodicals; 620.11
• DOI: 10.1016/j.mtcomm.2021.102352
• Languages: English
• ISSNs: 2352-4928

Abstract

Graphical abstract: Highlights: Hot deformation processing map of a FeCrMnN stainless steel was designed. Dynamic recrystallization occurred in temperature of 1100−1200 °C and strain rate of 0.1–1 s −1 . Decreasing temperature and increasing strain rate reduced dynamically recrystallized grain size. Unstable flow may occur at temperatures 800−950 °C and strain rates 0.1–10 s −1 . Abstract: The hot deformation characteristics of a FeCrMnN austenitic stainless steel containing 0.28 wt.% nitrogen (N) was investigated by hot compression tests using a Gleeble simulator in the temperature range of 800−1200 °C and at constant true strain rates of 0.01–10 s −1 with all specimens deformed to ∼0.9 true strain. The influence of deformation conditions on microstructural mechanisms and phase transformations was characterized. A processing map based on dynamic materials modelling (DMM) was designed and interpreted for predicting the domain of stable flow for safe, defect-free hot deformation. The results revealed the occurrence of dynamic recrystallization (DRX) in a domain extending over the temperature and strain rate ranges of 1100−1200 °C and 0.1–1 s −1, respectively, with the efficiency of power dissipation (η) of 45–55 %. Decreasing temperature and increasing strain rate led to a reduction in DRX grain size following microstructural reconstitution. Another small deterministic domain of 820−1000 °C and 0.01−0.05 s −1 was identified showing occurrence of partial DRX in shear bands leading to formation of a mixed microstructure. The instability criteria delineated the regime of unstable flow covering a large part of the processing map extending over low temperatures (800−950 °C) and high strain rates (0.1–10 s −1 ) that must be avoided during processing.