Influence of Heat Treatment on the Microstructures and Mechanical Properties of K465 Superalloy

摘要

The microstructures and mechanical properties of superalloy K465 under different heat treatment, including as as-cast, solution treatment and aging, were investigated. The results showed that γ' precipitates in as-cast condition exhibited two kinds of morphologies of fine regular cuboidal shape at dendritic arm and coarse irregular form in interdendritic region. MC carbides decomposed into M_6C carbides partly after 1210℃/4h solution treatment. The high temperature stress-rupture life can be improved obviously with the increasing cooling rate. When cooling rate was lower than 70℃/min, the room temperature tensile elongation increased with cooling rate increasing. When cooling rate was higher than 90℃/min the room temperature tensile elongation decreased with cooling rate increasing. The proper cooling rate of 70℃/min～90℃/min is advantageous for the achievement of excellent comprehensive properties. When aging treatments continued the regularization of γ' resulted in the improvement of stress-rupture life and the reduction of tensile elongation. The mechanical property gap between the solution treatment and aging can be decreased with increasing cooling rate.