Effect of hot rolling and heat treatment on structure and properties of high carbon Fe–Al alloys

Abstract

Iron–aluminium alloys with the following compositions, Fe–8.26 wt.% Al–0.46 wt.% C, Fe–7.2 wt.% Al–1.1 wt.% C, Fe–11.20 wt.% Al–0.5 wt.% C and Fe–10.83 wt.% Al–1.1 wt.% C were melted under a flux cover by air induction melting (AIM). The AIM ingots were subsequently processed through electroslag remelting (ESR). Both AIM and ESR ingots were hot forged and hot rolled at 1375 K to 92% reduction. ESR ingots exhibited better hot workability as compared with AIM ingots. This may be due to the axially oriented columnar grain structure relatively free from internal defects such as microporosity and non metallic inclusions observed in ESR ingots. About 14 ml thick ESR processed alloys in the hot-rolled condition also exhibited superior room temperature tensile elongation as compared with hot-rolled AIM alloys. This may be attributed to the comparatively homogeneous, clean ingot with a refined microstructure and a fine uniform distribution of Fe 3AlC 0.5 phase as observed after ESR. Further rolling of the ESR alloy to a 4-mm thickness has resulted in significant improvements in strength. The tensile elongation of hot rolled ESR alloys was reduced after heat treatment except in the case of Fe–7.2 wt.% Al–1.1 wt.% C alloy which exhibited a 17% improvement.