涡轮叶片合金筏化量化表征及寿命退化研究

针对单晶/定向凝固涡轮叶片服役过程中微观组织筏化及其造成的叶片力学性能劣化问题,发展了一种基于旋转割线方法的微结构筏化参数提取方法,并提出筏化状态的量化表征因子。对不同组织筏化和粗化状态的定向凝固高温合金开展高温低周疲劳试验,建立了量化筏化状态和合金疲劳寿命退化的映射关系。结果表明:无论是粗化还是筏化都会造成合金疲劳寿命的大幅劣化,所建立的镍基高温合金筏化量化因子能够有效地表征合金疲劳寿命的衰减。

Quantitative Characterization of Rafting State and Life Degradation of Superalloys for Turbine Blades

In order to solve the problem of microstructure rafting and mechanical properties degradation of single crystal/directionally solidified turbine blade in service,a method of extracting microstructure rafting parameters and quantitative characterization factors of rafting state was developed based on rotating secant method.High temperature and low cycle fatigue tests were carried out on directionally solidified superalloys with different rafting and coarsening states.The mapping relationship between rafting state and fatigue life degradation was established.The results show that the fatigue life of Ni-based superalloy will be greatly degraded by roughening or rafting,and the rafting quantitative factor can effectively characterize the fatigue life degradation of Ni-based superalloy.