Microstructure and mechanical properties of Fe–7Al based lightweight steel containing carbon

Abstract

The effect of carbon on the microstructure and mechanical properties of lightweight steel based on Fe–7 wt-%Al produced by air induction melting with flux cover is investigated. The ingots were hot worked to plates and were characterised. Steel containing 0.02 wt-%C exhibited a single phase microstructure Fe–Al(α), whereas steel containing 0.5 and 1.0 wt-% carbon exhibited a two-phase microstructure containing significant amounts of Fe3AlC0.5 precipitates in Fe–Al(α) matrix. Microhardness of the matrix decreases with increasing carbon content due to depletion of aluminium from the matrix to form Fe3AlC0.5 carbides. The bulk hardness, room temperature strength increases and tensile elongation decreases with increasing carbon content. However, at 873 K the improvement in strength as well as creep properties with increasing carbon content is marginal.