Research On The Preparation, Microstructure, Mechanical Properties And Hot Deformation Behavior Of FGH4169Superalloy

GH4169alloy is widely used in aviation, aerospace and nuclear power, oil field because of its high strength, oxidation resistance, irradiation resistance, thermal properties and good welding performance. Compared with the traditional preparation methods, GH4169prepared by a powder metallurgy method has the advantages of reducing macrosegregationFGH4169nickel-base superalloy was processed through powder metallurgy (P/M) hot isostatic pressing (HIP) route. The precipitation behavior of δ phase and mechanical properties of FGH4169superalloy were investigated by microscope, scanning electron microscope, differential scanning calorimeter, microhardness tester, electronic universal testing machine and creep testing machines. The hot deformation behavior of FGH4169superalloy was studied by single-stroke compression test on Gleeble3500test machine at the temperatures of950～1050℃and the strain rates of0.004～10s-1. The main conclusions are as followed:(1) Oxygen content of FGH4169superalloy powder prepared by plasma rotating electrode process (PREP) was0.0014%which was much lower than that of small size powder (below125μm). However, the particle size of superalloy powder was concentrated in the scale of190μm. Content of particle size below125μm was low. Thus, prior particle boundary (PPB) has less effect on HIPed FGH4169superalloy.(2) The temperature of solution treatment was in the range of940～1000℃. With solution temperature increasing, the content of δ phase reduced gradually. And precipitation of δ phase in the grain boundary and grain interior turned into the grain boundary mainly. Strength of FGH4169superalloy increased with the reduction of δ phase content, while corresponding elongation hasn’t changed much.(3) The yield strength and tensile strength of standard heat treatment (STD) FGH4169at room temperature were964and1125MPa, respectively. And the yield strength and tensile strength of direct aging treatment (DA) FGH4169at room temperature were1130and1312MPa, respectively. The elongation of STD sample was22.6%, higher than that of DA sample. Tensile properties at650℃showed the same trend.The yield strength and tensile strength of standard heat treatment (STD) FGH4169at650℃were923MPa and1116MPa, respectively. And the yield strength and tensile strength of direct aging treatment (DA) FGH4169at650℃were1093MPa and1245, respectively. The elongation of STD sample was21.5%, higher than that of DA sample.The stress rupture life of the STD sample at650℃,690MPa improved considerably due to solution heat treatment. DA sample showed notch sensitivity.(4) Original grains of HIPed FGH4169superalloy were severely stretched along the hot deformation direction under the deformation condition of lower temperature (950℃) and higher strain rate (10s-1). A small amount of recrystallization grains along original grain boundary formed "necklace" organization. With increasing temperature and decreasing strain rate, the amount of stretched grains reduced. Thus, dynamic recrystallization achieved completely and grains grew up obviously.(5) Relationship between peak flow stress and strain rate of HIPed FGH4169alloy could be described by constitutive equations below. in which(6) The suitable deformation conditions were at the temperature range from1010℃to1050℃with strain rate from0.01s-1to0.1s-1, and at the temperature of980℃with strain rate from0.004s-1to0.01s-1.