Relationship between Austenite‐Stabilizing Elements and Austenite Fraction in Near‐Rapidly Solidified Fe–Mn–Al–C Lightweight Steel

Abstract

A peritectic reaction (liquid + δ‐ferrite → γ‐austenite) and eutectoid reaction (γ‐austenite → α‐ferrite + κ carbide) occur in the Fe–Mn–Al–C lightweight steel. Experimental results show that the main constituent phase of the near‐rapidly solidified Fe–Mn–Al–C lightweight steel is γ‐austenite and/or δ‐ferrite in this study, and the eutectoid reaction is restrained by the rapid cooling rate. With the increase of C content, the γ‐austenite fraction of near‐rapidly solidified medium‐Mn and high‐Mn Fe–Mn–Al–C lightweight steels increase significantly. However, in the early study, the increased Mn content had little effect on the γ‐austenite fraction of the near‐rapidly solidified Fe–(8/12/16)Mn–9Al–0.8C steel strips. This study attempts to reveal the reasons for the different effects of Mn and C on Fe–Mn–Al–C lightweight steel strip under near‐rapid solidification. It is found that the γ‐austenite fraction of the near‐rapidly solidified Fe–Mn–Al–C steel strip is closely related to the γ‐austenite fraction at the end of equilibrium solidification. This suggests that the main constituent phase of lightweight steel strip depends on its liquid–solid phase transformation under near‐rapid solidification and is seldom affected by solid phase transformation.