The role of active elements in Fe-Cr-Al alloys for heating element applications

摘要

The role of active elements (zirconium, cerium and yttrium) in grain growth and its subsequent effect on room-temperature tensile fracture behaviour of Fe-Cr-Al alloys has been investigated. The alloys containing active elements exhibited improved resistance to grain growth. Yttrium-containing alloy retained higher room-temperature tensile ductility even after heating at higher temperatures because of its superior resistance to grain coarsening. All the alloys, with and without active elements, exhibited a sudden drop in room-temperature tensile ductility, with concommitant change in fracture mode from dimple rupture to cleavage, in a narrow band of 39–44µm grain size. The ductile-brittle transition temperatures (DBTT) of these alloys were found to be 150°C and 215°C for grain sizes 25µm and 100µm respectively. The accelerated life test showed that the alloys containing active elements exhibited longer