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Free keywords:
Carbides; Climate change; Ductility; Microstructure; Tensile strength; Thermodynamic stability; Titanium alloys, Elevated temperature; High thermal stability; High-temperature ductility; Light-weight steels; Multi-phase structures; Multiphase microstructure; Sustainable solution; Ultimate tensile strength, Aluminum coated steel
Abstract:
The global demand for lightweight design is increasing to provide sustainable solutions to counteract climate change. We developed a novel Ti-bearing lightweight steel (8 lower mass density than general steels), which exhibits an excellent combination of strength (491 MPa ultimate tensile strength) and tensile ductility (31) at elevated temperature (600 °C). The developed steel is suitable for parts subjected to high temperature at reduced dynamical load. The composition of the developed steel (Fe–20Mn–6Ti–3Al–0.06C–NbNi (wt)) lends the alloy a multiphase structure with austenite matrix, partially ordered ferrite, Fe2Ti Laves phase, and fine MC carbides. At elevated temperature (600 °C), the ductility of the new material is at least 2.5 times higher than that of conventional lightweight steels based on the Fe–Mn–Al system, which become brittle at elevated temperatures due to the inter/intragranular precipitation of κ-carbides. This is achieved by the high thermal stability of its microstructure and the avoidance of brittle κ-carbides in this temperature range. © 2021 Elsevier B.V.
