Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7973935 | Materials Science and Engineering: A | 2018 | 30 Pages |
Abstract
The ductility and formability properties of three high-Mn TWIP steels were investigated under quasi-static and high-speed deformation conditions. The ductility was evaluated from conventional and Hopkinson split-bar tensile tests at 1250â¯sâ1 and the stretch formability was evaluated using Erichsen tests made with a special high-speed electro-hydraulic forming machine at about 1000â¯sâ1. The data were related to microstructural features revealed using electron backscatter diffraction and X-ray diffraction. Furthermore, the stacking fault energy (SFE) was estimated using a thermodynamic approach. It was found that the 0.6C-22Mn and 0.2C-21Mn-0.23N steels (compositions in wt%) with SFEs of 23-24â¯mJ/m2 exhibited good elongation and a large Erichsen index at both low and high strain rates. These were attributed to intensive mechanical twinning though partly replaced by dislocation slip in deformation bands in the high-speed tests. However, it was noticed that the high-speed stretching failure of these TWIP steels occurred in the uniform elongation range without diffuse necking. In the austenitic - ferritic 21Mn-3Al-3Si steel strain-induced martensite was formed, but the ferrite phase seemed to impair formability.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
A.S. Hamada, A. Kisko, A. Khosravifard, M.A. Hassan, L.P. Karjalainen, D. Porter,