在对一系列高合金化模型合金进行系统比选研究的基础上, 发展了新型的GH4065变形高温合金, 该合金化学成分与René 88 DT合金类似, 并针对铸锻制备工艺的要求进一步实施了优化. 研制结果表明, 应用三联低偏析熔铸和多重循环热机械处理等新型技术生产的GH4065合金, 适用于制备先进航空发动机关键热端转动部件, 综合性能完全满足高压压气机盘和低压涡轮盘的工况要求, 必要时可以作为高压涡轮盘的高可靠性、低成本解决方案. 随着变形高温合金材料和制备工艺的发展, 应用铸锻工艺制备的高性能涡轮盘材料能够满足先进航空发动机的技术要求.

Much attention has been paid to the development of more advanced materials for high-pressure compressor and turbine discs of gas turbine engines. A high performance wrought superalloy GH4065 for disc applications has been recently developed based on the comprehensive evaluation of a series of model alloys with characteristic chemical composition, lattice parameter, particularly γ’ volume fraction. The concentration of major alloying elements of GH4065 is closely similar with René 88 DT and specifically optimized considering the demands of ingot metallurgy technologies. Therefore, GH4065 can be considered as an ingot metallurgy version of powder metallurgy René 88 DT. Large scale vacuum arc remelting (VAR) ingots of GH4065 alloy with diameter up to 508 mm have been produced via standard triple melting techniques. Micro-scale segregation of alloying elements on large VAR ingot has been effectively suppressed due both to optimized alloying elements concentration and to improved melting techniques. Ultra-low carbon content (less than 0.02% in mass fraction) significantly decreases the dendritic segregation tendency of certain alloying elements and promotes the uniformity of microstructures. VAR ingot of GH4065 exhibits extraordinary hot plasticity, ingot conversion can be accomplished using conventional open die forging procedure. Fine and uniform γ+γ’ duplex structures can be obtained on billets and disc forgings via a newly developed multi-cycle thermomechanical processing method. The flow stress data show that the formation of γ+γ’ microduplex results in a significant decrease of flow stress in comparison with γ’ dispersion structures under exactly the same deformation conditions. The distribution of strain rate sensitivity m in relationship with temperature and strain rate accurately identifies a specific domain within which γ+γ’ microduplex exhibits superplasticity. Full-scale turbine discs of GH4065 alloy with diameter of 630 mm achieve an optimal combination of creep resistance, fatigue lifetime and ductility. GH4065 discs exhibit extraordinary microstructural and property stability during prolonged thermal exposure, which means that dendritic segregation has been successfully restricted to an acceptable level. The results reveal that highly alloyed disc alloys produced via ingot metallurgy techniques exhibit lower costs and higher productivity, and can still meet the ever increasing demand of high performance gas turbine engines.