Effect of carbon content on elevated temperature stability and tensile properties of Fe-8.5 Al Alloys

Fe-8.4Al-0.04C, Fe-8.26Al-0.46C and Fe-8.35Al-1.1C alloys were prepared by a combination of air induction melting and electroslag remelting. The low ( 0.04 wt.%) carbon alloy exhibited microcracks therefore it was not studied further. The ESR ingots of high (0.46 and 1.1 wt.%) carbon alloys exhibited a significant amount of Fe3AlC0.5 precipitation. The cast ESR samples of F e-8.26Al-0.46C and Fe-8.35Al-1.1 C were placed in a hearth furnace at 873, 1073 and 1273 K for 24 h and then furnace cooled. The high carbon alloys do not undergo decarburization and exhibit stable microstructure up to 873 K. Decarburization appears to be a problem only after exposure at temperature s of 1073 K and above. The ESR Fe-8.26Al-0.46C alloy exhibited greater elon gation and significantly better elevated temperature strength up to 873 K t han those reported for cast VIM low carbon multicomponent alloy with simila r Al content. This may be due to the presence of a large volume fraction of stable Fe3AlC0.5 precipitates. All the high carbon alloys exhibit a sharp drop in strength at 873 K regardless of carbon content. These alloys are th erefore targeted for potential structural application at or below 873 K. (C ) 2000 Elsevier Science S.A. All rights reserved.