Wrought Fe-Cr-Al alloys

It is recommended that semifinished blanks from Fe-Cr-Al alloys (Fechrals) with or without disperse strengthening-phase additions should be manufactured from alloy powders (rather than from mechanical mixtures); the blanks should be additionally consolidated by hot isostatic pressing, and the resultant rods subjected to hot plastic working by extrusion. Hot isostatic pressing increases the processing ductility of Fe-Cr-Al alloys, reduces the size of their ferrite grain, and improves their mechanical properties. Free forging of blanks produced by hot isostatic pressing does not ensure good quality of rods: Their mechanical properties show scatter due to large grain size variations and the presence of microcracks. The mechanical and physical properties of Fe-Cr-Al alloys produced by powder metallurgy techniques are virtually identical with those of cast alloys of the same compositions. At the same time, P/M alloys are less prone to grain growth at t>900°C. Additional strengthening with disperse refractory oxides (2 wt. % TiO2 or ZrO2) increases about 1.5–2 times the strength of Fe-10A1-25Cr alloys at room and high temperatures right up to 1200°C.