Creep in high Al ferrite based low density steel

Abstract Low density steels have attracted the attention of researchers across the globe as substitute alloys in structural and locomotive applications with promising mechanical properties and reduced density. Most of the research in low density steels is concentrated on room temperature properties after the thermomechanical processing of the same. In the present study, a high Al Fe-11Al-5Mn-0.1C low density steel was melted by vacuum arc melting in argon atmosphere. The as cast alloy was homogenized at 1200 °C and then hot rolled from 20 mm to 2 mm at 1100 °C. Hot rolled strips were annealed at 1000 °C for 1 h followed by furnace cooling. After thermomechanical processing, creep testing of alloy samples was carried out at 600 °C for 50 MPa and 100 MPa stress. The processed alloy has shown a total creep life of 6.21 h and minimum creep rate of 8.5 × 10−1 h−1 for 100 MPa stress and for a stress of 50 MPa, creep life of 1005.1 h with minimum creep rate of 1.4 × 10−3 h−1. A dominating tertiary creep with appreciable secondary and negligible primary creep regime was observed. Fracture occurred due to cavitation at ferrite-kappa carbide interface. Ductile mode of fracture with fine dimples was observed.