TY - JOUR
T1 - Synergistic deformation pathways in a TWIP steel at cryogenic temperatures
T2 - in situ neutron diffraction
AU - Tang, Lei
AU - Wang, Minshi
AU - Liu, Huibin
AU - Kabra, Saurabh
AU - Chiu, Yulung
AU - Cai, Biao
AU - Wang, Li
PY - 2020/11
Y1 - 2020/11
N2 - High manganese steels are promising candidates for applications in cryogenic environments. In this study, we investigate the mechanical and microstructural responses of a high manganese twinning induced plasticity (TWIP) steel at a low-temperature range (from 373 to 77 K) via in situ neutron diffraction qualification and correlative microscopy characterization. During plastic deformation, stacking fault probability and dislocation density increased at a faster rate at a lower temperature, hence, higher dislocation density and denser mechanical twins were observed, confirmed by microscopic observation. Stacking fault energy was estimated, dropping linearly from 34.8 mJm−2 at 373 K to 17.2 mJm−2 at 77 K. A small amount of austenite transferred to martensite when deforming at 77 K. The contributions to flow stress from solutes, grain boundary, dislocation, and twinning were determined at different temperatures, which shows that the high work strain hardening capacity of the TWIP steel originates from the synergetic strengthening effects of dislocations and twin-twin networks. These findings reveal the relationship among stacking fault energy, microstructure, and deformation mechanisms at the low-temperature range, paving a way in designing TWIP steels with the superb mechanical performance for cryogenic applications.
AB - High manganese steels are promising candidates for applications in cryogenic environments. In this study, we investigate the mechanical and microstructural responses of a high manganese twinning induced plasticity (TWIP) steel at a low-temperature range (from 373 to 77 K) via in situ neutron diffraction qualification and correlative microscopy characterization. During plastic deformation, stacking fault probability and dislocation density increased at a faster rate at a lower temperature, hence, higher dislocation density and denser mechanical twins were observed, confirmed by microscopic observation. Stacking fault energy was estimated, dropping linearly from 34.8 mJm−2 at 373 K to 17.2 mJm−2 at 77 K. A small amount of austenite transferred to martensite when deforming at 77 K. The contributions to flow stress from solutes, grain boundary, dislocation, and twinning were determined at different temperatures, which shows that the high work strain hardening capacity of the TWIP steel originates from the synergetic strengthening effects of dislocations and twin-twin networks. These findings reveal the relationship among stacking fault energy, microstructure, and deformation mechanisms at the low-temperature range, paving a way in designing TWIP steels with the superb mechanical performance for cryogenic applications.
KW - Cryogenic temperatures
KW - Deformation pathways
KW - Deformation twinning
KW - Neutron diffraction
UR - http://www.scopus.com/inward/record.url?scp=85091941996&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2020.09.075
DO - 10.1016/j.actamat.2020.09.075
M3 - Article
SN - 1359-6454
VL - 200
SP - 943
EP - 958
JO - Acta Materialia
JF - Acta Materialia
ER -