热处理冷速对FGH97盘件显微组织和蠕变性能的影响

Effect of Solution Cooling Rate on Microstructure and Creep Properties of FGH97 Nickel-base Superalloy of Large Turbine Disk

摘要:

对FGH97粉末高温合金盘件进行热处理处理,采用光学显微镜,扫描电子显微镜,能谱仪和蠕变试验机研究了不同固溶冷速下合金的显微组织、蠕变性能、蠕变变形方式和蠕变断裂机制。研究表明：随固溶冷速的增加,γ′相尺寸减小,碳化物由连续析出变为颗粒状弥散析出,晶界碳化物为富Ti、Nb、Hf的MC相。在750℃/450MPa蠕变试验条件下,冷速为94℃/min的样品性能明显优于冷速为43℃/min的样品。FGH97 粉末高温合金在750℃/450MPa条件下的蠕变机制为通过切割γ′相产生塑性变形,在晶界处产生应力集中导致裂纹的萌生,裂纹沿着晶界碳化物扩展,最终导致材料的断裂,弥散颗粒状分布的碳化物能有效抑制微裂纹的贯通。

Abstract:

FGH97 nickel-base superalloy were processed at different solution cooling rates, then the microstructure and creep behavior of FGH97 nickel-base superalloy were studied by optical microscope, scanning electron microscope, energy disperse spectroscopy and creep testing machine. The results show that the grain size decreases, the size of γ′ precipitates decreases and the carbide precipitates change from continuous to discrete with the increasing solution cooling rate, and GB carbides are composed of (Ti, Nb, Hf)-rich. The creep performance of the alloy with a solution cooling rate of 94 ℃/min was significantly better than that with a cooling rate of 43 ℃/min under 750℃/450MPa.γ′ cutting is the deformation mechanism of FGH97 alloy under 750℃/450MPa, stress concentration at grain boundary leads to initial cracks, then crack propagates along grain boundary and finally leads to fracture. The disperse distribution carbides on grain boundary can inhibit the propagation of microcracks.