Lai Z.-HLin Y.-TSun Y.-HTu J.-FHUNG-WEI YEN2022-11-162022-11-16202213596462https://www.scopus.com/inward/record.uri?eid=2-s2.0-85126395889&doi=10.1016%2fj.scriptamat.2022.114629&partnerID=40&md5=57e78db1ab8a403290a9d0f79e3fbd2chttps://scholars.lib.ntu.edu.tw/handle/123456789/625356This study reported a novel hydrogen-induced ductilization in an austenitic lightweight twinning-induced plasticity (TWIP) steel (Fe-1C-25Mn-5.5Al-3Si, in wt. %). This phenomenon was irrelevant to strain rate or global work hardening rate. In fact, the stacking fault energy (SFE), 49.5 mJm−2, of the steel is an appropriate value for hydrogen-induced ductilization. This SFE was reduced by hydrogen and deformation twin was enhanced in the hydrogen-rich surface layer during deformation. Such twinning-strengthened surface limits formation of strain localization and allows extra deformation. Besides, this SFE is high enough so that martensitic transformation and hydrogen-enhanced intergranular cracking were absent, making the steel free from hydrogen embrittlement. This work provides a new concept that SFE/twinability engineering not only prevents hydrogen embrittlement but enables hydrogen-induced ductilization. © 2022Deformation twin; Hydrogen embrittlement; hydrogen-induced ductilization; Lightweight TWIP steel; Stacking fault energyAustenite; Austenitic stainless steel; Austenitic transformations; Deformation; High strength steel; Hydrogen; Martensitic transformations; Plasticity; Stacking faults; Strain rate; Textures; Twinning; Austenitic; Deformation twin; Fault energy; Hydrogen-induced ductilization; Lightweight twinning-induced plasticity steel; Stacking fault energy; Strain-rates; Surface layers; Twinninginduced plasticity (TWIP) steel; Work hardening rate; Strain hardeningjournal article10.1016/j.scriptamat.2022.1146292-s2.0-85126395889