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

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-10.8 3 wt.% Al-1.1 wt.% C were melted under a flux cover by air induction meltin g (AIM). The AIM ingots were subsequently processed through electroslag rem elting (ESR). Both AIM and ESR ingots were hot forged and hot rolled at 137 5 K to 92% reduction. ESR ingots exhibited better hot workability as compar ed with AIM ingots. This may be due to the axially oriented columnar grain structure relatively foe from internal defects such as microporosity and no n metallic inclusions observed in ESR ingots. About 14 mi thick ESR process ed alloys in the hot-rolled condition also exhibited superior room temperat ure tensile elongation as compared with hot-rolled AIM alloys. This may be attributed to the comparatively homogeneous, clean ingot with a refined mic rostructure and a tine uniform distribution of Fe3AlC0.5 phase as observed after ESR. Further rolling of the ESR alloy to a 4-mm thickness has resulte d in significant improvements in strength. The tensile elongation of hot ro lled 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. (C) 2001 Els evier Science B.V. Ah rights reserved.