一级时效对DD3单晶高温合金蠕变性能的作用

Effects of First Aging Stage for Creep Properties of DD3 Single Crystal Superalloys

根据DD3合金的热分析和相分析结果，设计了以增大γ’平均尺寸、改善γ’尺寸分布和提高析出相含量为目的的时效和固溶处理制度，进行了提高DD3单晶高温合金蠕变性能的热处理工艺研究。结果表明，增加一级高温时效处理可使γ’相尺寸明显增大；高温时效温度高于1080℃时，γ’相过分长大；1060℃／4h时效处理后，γ’相组织最优；配合在1265℃／4h的固溶处理，γ’相含量得到提高的同时，合金蠕变、拉伸性能优异。组织与性能研究证明，加入一级高温时效处理的新工艺可使DD3合金组织得到明显优化，760～1038℃范围内的蠕变性能获得显著提高。根据该结果，新的热处理工艺确定为：1265℃／4h，AC＋1060℃／4h，AC＋870℃／32h。

According to the results of differential thermal analysis and physicochemical phase analysis to casting and standard heat treatment samples, optimized solution and aging heat treatment regimes designed to improve creep properties of DD3 single crystal su- peralloys were investigated. Experiments on the heat treatment regimes show a high temperature aging treatment addition can significantly increase the γ＇ size and improve its distribution, but γ＇ phases will be over-ripening, even grow to rafts when aging temperature in excess of 1080℃. When solution heat treated at 1265℃ , with γ＇ mass fractions increasing, DD3 alloy exhibits best creep rupture and tensile properties. The studies on microstruetures and mechanical properties have clarified that the new heat treatment with a first high temperature aging addition resulted in optimized microstructure and remarkably improved creep properties at 760 - 1038℃. As a result that the new heat treatment： 1265℃/4h, AC ＋ 1060℃/4h, AC ＋ 870℃/32h were designed.