Effect of carbon and processing on structure and mechanical properities ofFe-11 wt.% Al alloy

Ingots of Fe-Al alloys containing 11 wt.% Al and 0.5 and 1.1 wt.% C were pr epared by a combination of air induction melting with flux cover (AIM) and electroslag remelting (ESR). The ESR ingots were hot forged at 1373 K to 53 % reduction and subsequently hot rolled at 1373 K to 53% rolling reduction. The cast ESR samples were placed in a hearth furnace at 873, 1073 and 1273 K for 24 h then furnace cooled to room temperature. The Fe-ll wt.% Al allo y containing 1.1 wt.% C exhibited a significant higher yield strength at te st temperature up to 773 K than alloy containing 0.5 wt.% C. This may be at tributed to the presence of large amount of hard Fe3AlC0.5 precipitates in the alloy. The thermo-mechanical processing of cast ESR ingots has resulted in significant improvement in room temperature tensile ductility. This may be due to breaking of cast dendritic structure and more uniform distributi on of Fe3AlC0.5 precipitates. These high carbon Fe-11 wt.% Al alloys exhibi ted excellent resistance to decarburization up to 1273 K because of the for mation of continuous protective Al2O3 film on the surface. It would appear from the present work that thermo-mechanically processed high (1.1 wt.%) ca rbon ESR alloy exhibit an attractive combination of properties. (C) 2000 El sevier Science S.A. All rights reserved.