Abstract
In this study, three cooling rates, namely, Argon cooling, air cooling and furnace cooling after solution heat treatment of directionally solidified CM-247LC superalloy were proposed to explore the high temperature/low stress (982°C/200MPa) creep behavior. Standard heat treatment schemes of DS CM-247LC superalloy are solution treatment at 1260°C for 2 hour, then first aging at 1079°C for 4 hour and followed by second aging at 871°C for 20 hour. Results show that Argon cooling specimen provided the longest creep rupture life, which exceeds that of the air cooling specimen around 40 hour; whereas the creep rupture life of furnace cooling specimen was the shortest one of 100 hour, which is shorter than that of the air cooling specimen around 40 hour. Rupture strains of all three specimens were almost identical around 20%. Microstructural differences of gamma prime morphology were observed to explain the differences of creep rupture life. © (2014) Trans Tech Publications, Switzerland.