Design of a hot deformation processing map for a Ni-free, N-bearing austenitic stainless steel
Khorshidi, H.; Kermanpur, A.; Rastegari, H.; Ghassemali, E.; Somani, M. C. (2021-04-22)
Khorshidi, H., Kermanpur, A., Rastegari, H., Ghassemali, E., & Somani, M. C. (2021). Design of a hot deformation processing map for a Ni-free, N-bearing austenitic stainless steel. Materials Today Communications, 27, 102352. https://doi.org/10.1016/j.mtcomm.2021.102352
© 2021 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/.
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2022020317444
Tiivistelmä
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.
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