EFFECT OF HOT-WORKING ON ROOM-TEMPERATURE MECHANICAL-PROPERTIES AND STRESS-RUPTURE BEHAVIOR OF ESR PROCESSED FE-16WT-PERCENT-AL INTERMETALLIC ALLOYS

The effect of hot working (forging) on structure and mechanical proper ties of electroslag remelted (ESR) Fe3Al based intermetallic alloys co ntaining approximately 16 wt% (28 at%) aluminium and 0.013 to 0.50 wt% carbon are reported. The ESR alloys having low (0.013 to 0.06 wt%) ca rbon content were severely cracked during forging probably due to the presence of pre-existing microcracks. ESR ingots with high (0.14 to 0. 50 wt%) carbon content were successfully forged at 1000 degrees C. At high (60% or more) forging reductions the cast columnar structute of E SR alloys was transformed into recrystallized grain structure. The roo m temperature mechanical properties did not improve significantly afte r forging. During creep and stress-rupture tests carried out at 600 de grees C and 140 MPa, the cast ESR ingot with columnar structure exhibi ted lower minimum creep rate and higher creep life than those exhibite d by the corresponding forged ingots with recrystallized grain structu re. There is only a marginal improvement in creep life with increase i n carbon content from 0.14 to 0.50 wt%. The stress-ruptured specimens exhibited predominantly ductile dimple failure with elongations in exc ess of 50%. The creep and stress-rupture properties of the alloys with high (0.14 to 0.50 wt%) carbon contents are better than those reporte d for wrought Fe-16 wt%Al alloys with low (< 0.01 wt%) carbon contents . This may be attributed to the presence of uniformly distributed Fe3A lC precipitates as well as the interstitial carbon present in the allo ys.