Thermomechanical processing of blades and disks can become challenging when the microstructure of the material consists of a high volume fraction of strengthening phases. In Rene 65, the precipitate volume fraction is 40 pct in the as-forged condition. The microstructure consists of a bimodal/trimodal γ′ precipitate distribution on the grain boundaries and intergranually. In order to control grain size and reduce hardness, primary γ′ should be present on the grain boundaries and the secondary and tertiary precipitates should be coarse. In this work, an attempt to optimize the heat treatments that coarsen those two populations by implementing tools from experimental design is attempted. Two sample categories were examined with different thermomechanical histories, one deformed and one deformed and annealed, in order to verify if the ultimate heat treatment can be applied at different processing steps. The results confirm that there is a definite effect of the original microstructure, since there were different heat treatments that were proven to be the most effective to reduce hardness for the two conditions. Microstructural analysis revealed precipitate splitting and coralloid microstructures were observed for the first time in this alloy. Two mechanisms are proposed for the reduction of hardness depending on the initial microstructure.

当材料的微观结构由高体积分数的强化相组成时，叶片和磁盘的热机械加工将变得充满挑战。在Rene 65，在锻造状态下，沉淀物体积分数为40 pct。显微组织由晶界和晶间的双峰/三峰γ '沉淀物分布组成。为了控制晶粒尺寸并降低硬度，原生γ′应存在于晶界上，次生和三次生沉淀应较粗。在这项工作中，尝试通过实施来自实验设计的工具来优化使这两个族群粗化的热处理。检查了两种具有不同热机械历史的样品类别，一种变形，另一种变形并退火，以验证是否可以在不同的处理步骤中进行最终热处理。结果证实了原始微观结构的确定作用，因为事实证明，在这两种情况下，不同的热处理方法均能最有效地降低硬度。显微组织分析表明，该合金首次观察到析出物分裂和珊瑚状显微组织。