Microstructure, properties and crystallographic orientation of novel austenitic Fe–26Mn-3.4Cr-0.4C steel under hot torsion process
An experimental austenitic twin-induced plasticity (TWIP) steel was deformed under hot torsion tests. Two different total equivalent strains (2.2 and 2.6) were employed in order to raise its yield strength while keeping reasonable toughness. The material was isothermally strained at 900 °C with a lo...
| Authors: | , , , , , , , |
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| Format: | article |
| Publication Date: | 2023 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/389709 |
| Online Access: | https://hdl.handle.net/2117/389709 https://dx.doi.org/10.1016/j.msea.2023.145206 |
| Access Level: | Open access |
| Keyword: | Materials--Mechanical properties Materials--Propietats mecàniques Àrees temàtiques de la UPC::Enginyeria dels materials |
| Summary: | An experimental austenitic twin-induced plasticity (TWIP) steel was deformed under hot torsion tests. Two different total equivalent strains (2.2 and 2.6) were employed in order to raise its yield strength while keeping reasonable toughness. The material was isothermally strained at 900 °C with a low strain rate of 0.05 s-1. The effects of torsional deformation on the microstructure, texture and mechanical properties of the TWIP steel were investigated and compared with the as-received samples. X-Ray Diffraction (XRD) measurements were performed to identify the phases present in the metal before and after the thermomechanical process. Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), Orientation distribution function (ODF) analysis and tensile experiments complemented the investigation of this research. The main deformation mechanism changed from conventional sliding inside the grain to nucleated twinning from the grain boundaries, which led to the decrease of the grain size to less than 1 µm (UFG - Ultrafine Grains). The results indicate that the transition in the deformation mechanisms is dependent on grain size associated with the flow profile of the material. This was due to changes in the dislocation density within the grain and the movement of dislocations around the yield point. No martensitic transformation was detected during the strain and neither from the twinning mechanism in the microstructure after the torsion deformation. The best balance between high strength and good ductility (920 MPa and 52%) was obtained after the total equivalent strain of 2.6. It was verified that the employed thermomechanical schedule affects the displacement of the substructure with the formation of sub-grains influencing the hardening behavior, texture and yield strength of the metal. |
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