Effect of heat treatment on microstructure and high temperature tensile properties of cast nickel-base superalloy with high W, Mo and Nb contents

摘要

The microstructural features and high temperature tensile properties of M963 superalloy at as-cast, as-solu-tioned and as-aged conditions were investigated in detail. The results show that the solution treatment at 1 220℃ for 4 h, AC causes an increase in high temperature yield strength but a drastic drop in high temperature ductility due to the precipitation of both the secondary carbide M_6C along grain boundaries and at the interdendritic regions and very fine γ′ particles in the dendrite cores. Aging treatment following the solution treatment can improve the high temperature tensile properties of M963 superalloy due to the coarsing of the γ′ precipitate. One stage aging at 850℃ for 16 h following the solution treatment causes an increase in both strength and ductility of alloy M963, and two-stage aging of 1089℃/2 h, AC plus 850℃ /16 h, AC following the solution treatment further increases the ductility of alloy M963 but slightly decreases its strength.