Investigation on a ramp solution heat treatment for a third generation nickel-based single crystal superalloy

The solution effects of a series of traditional stepwise solution heat treatments (SSHTs) and a ramp SHT were investigated. The results show that as the dwelling time increases, the residual segregation reduces after SSHT and the uniformity of size distribution of γ′ particles increases after subsequent aging treatment. Less residual segregation was obtained after the ramp SHT than SSHT. The advantages of ramp SHT are proposed as follows: higher permissible solution temperature without incipient melting, lower residual segregation due to more effective dissolution, more homogenous size distribution of γ′ after aging treatment, and 1.3-times longer rupture life at 1100 °C and 150 MPa. The dynamic ramp solution heat treatment is more appropriate due to the continuously increasing incipient melting temperature controlled by kinetic diffusion.