Shivkumar Khaple

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.

Microstructural Characterisation of Ti Containing Fe-7Al-0.35C Based Low-Density Steel

In this paper, the role of Ti on the in-situ formation of carbides and its effect on the microstructure of Fe-7Al-0.35C alloy have been investigated. Initially, Thermo-Calc software was used to predict the phases present in the alloys which were validated by experimental work. Vacuum arc remelting process was used to make an alloy pancake of 10-mm thickness, which was hot-rolled to 2-mm thickness. The alloys were characterised by X-ray diffraction, optical, scanning electron microscope and electron probe micro-analysis. The results show that all the alloys exhibit two types of TiC precipitates, which are dark cuboidal as primary and dark acicular type as secondary precipitates along with grey-coloured needle-shaped κ-carbide precipitate in α(Fe–Al) matrix. The carbon present in the alloy is partitioned between TiC and κ-carbide precipitates. Addition of Ti has also resulted in grain refinement of all the alloys.