The influence of stacking fault energy on the microstructural and strain-hardening evolution of Fe–Mn–Al–Si steels during tensile deformation. (November 2015)

• Record Type: Journal Article
• Authors: Pierce, D.T.; Jiménez, J.A.; Bentley, J.; Raabe, D.; Wittig, J.E.
• Is Part Of: Acta materialia. Volume 100(2015)
• Page Start: 178
• Page End: 190
• Publication Date: 2015-11
• Subjects: TWIP steel -- TRIP steel -- Stacking-fault energy -- Plasticity mechanisms -- Twinning; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2015.08.030
• Languages: English
• ISSNs: 1359-6454

Abstract

Graphical abstract: Abstract: Understanding the relationship between the stacking-fault energy (SFE), deformation mechanisms, and strain-hardening behavior is important for alloying and design of high-Mn austenitic transformation- and twinning-induced plasticity (TRIP/TWIP) steels. The present study investigates the influence of SFE on the microstructural and strain-hardening evolution of three TRIP/TWIP alloys (Fe–22/25/28Mn–3Al–3Si wt.%). The SFE is increased by systemically increasing the Mn content from 22 to 28 wt.%. The Fe–22Mn–3Al–3Si alloy, with a SFE of 15 mJ m −2, deforms by planar dislocation glide and strain-induced ε hcp -/ α bcc -martensite formation which occurs from the onset of plastic deformation, resulting in improved work-hardening at low strains but lower total elongation. With an increased SFE of 21 mJ m −2 in the Fe–25Mn–3Al–3Si alloy, both mechanical twinning and ε hcp -martensite formation are activated during deformation, and result in the largest elongation of the three alloys. A SFE of 39 mJ m −2 enables significant dislocation cross slip and suppresses ε hcp -martensite formation, causing reduced work-hardening during the early stages of deformation in the Fe–28Mn–3Al–3Si alloy while mechanical twinning begins to enhance the strain-hardening after approximately 10% strain. The increase in SFE from 15 to 39 mJ m −2 results in significant changes in the deformation mechanisms and, at low strains, decreased work-hardening, but has a relatively small influence on strength and ductility.