以涡轮叶片用DZ125合金为研究对象, 通过蠕变中断实验模拟涡轮叶片的服役损伤, 并分别在1230, 1240和1250 ℃进行恢复热处理, 随后再次进行与恢复热处理前相同条件下的蠕变中断实验, 对比研究了恢复热处理对DZ125合金蠕变退化组织与性能的影响. 结果表明, DZ125合金在980 ℃, 207 MPa条件下经蠕变中断实验与恢复热处理后, 引发再结晶的临界应变量介于3.5%~10.0%之间. 1230 ℃固溶热处理部分消除了合金在1.0%蠕变过程中形成的粗大γ'相, 导致其经2次时效处理后的基体组织中γ'相大小不均匀, 从而部分恢复其原有性能. 固溶温度进一步提高至1240~1250 ℃, 不仅消除了粗大γ'相而且显著降低了残余共晶γ'相含量, 并在时效处理后获得均匀组织. 因此, 恢复热处理的效果得到显著提高, 达到甚至超过原有性能.

The degradation of microstructure and property in turbine blades of aircraft engines is inevitable during their service. Usually, rejuvenation heat treatment is applied to regenerate the original microstructure for extending the service life of blades and improve economic returns. To date, systematic investigations about rejuvenation heat treatment of the directionally-solidified superalloys are limited. In this work, the effect of rejuvenation heat treatment on the degraded microstructure and property of DZ125 superalloy damaged by creep was investigated. The interrupted creep test was first conducted on DZ125 superalloy to simulate the damage of turbine blades during their service. Three rejuvenation heat treatments with the solution temperature at 1230, 1240 and 1250 ℃ were applied to the interrupted creep specimen. Then, the rejuvenated specimens were retested, and their microstructures as well as creep properties were compared with those of the initial interrupted creep tests. The results showed that no recrystallization occurred after the interrupted creep tests at 1.0% and 3.5% strain followed by rejuvenation heat treatment, and the critical strain for the formation of the recrystallization was between 3.5%~10.0%. The solution treatment at 1230 ℃ partially dissolved the coarse γ' phase caused by creep deformation, caused a nonuniform microstructure of γ /γ' matrix after aging treatments, and resulting in partially recovering the baseline creep property. However, the solution treatment at 1240 and 1250 ℃ could not only dissolve the coarse γ' phase but also reduce the fraction of residual γ' eutectic significantly, and then regain a uniform microstructure of γ /γ' matrix after aging treatments. Hence, the effect of rejuvenation was further improved, maintaining or exceeding the baseline creep property.