Isothermal forging(IF)is an effective method for forming difficult-to-deform materials like P/M superalloys.Understanding the isothermal compression microstructural evolution mechanism of a novel P/M s-peralloy provid...Isothermal forging(IF)is an effective method for forming difficult-to-deform materials like P/M superalloys.Understanding the isothermal compression microstructural evolution mechanism of a novel P/M s-peralloy provides the basis for its optimized IF planning.In this study,the isothermal compression tests of a novel fine-grained P/M nickel-based superalloy were carried out at 1000-1150℃with strain rates of 0.001-0.01 s^(−1).The results indicated that the alloy exhibits three distinct flow characteristics:continuous softening after reaching the peak stress,near-steady superplastic flow,and discontinuous hardening,corresponding to different strain rate sensitivity exponent(m)values.Varied microstructural evolution mechanisms,including grain boundary sliding(GBS),dynamic recrystallization(DRX),and grain growth,are dominated in different m-value domains.Meanwhile,different roles of primaryγ’play in microstruc-tural evolution were clarified.A moderate fraction of primaryγ’with 8.5%-14.2%can well coordinate the GBS and hinder excessive grain growth at a high m value domain(m>0.4).When 0.2<m<0.4,the role of the primaryγ’is changed to promote dislocation accumulation,accelerating the nucleation of DRXed grains.As the primaryγ’is dissolved at 1150℃,obvious grain growth was observed after compression.Work hardening effect by overgrown grains competed with DRX softening results in the discontinuous rising stress.展开更多
FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to p...FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process （PREP）, hot isostatic pressing （HIP） at super-solvus temperature and a sub-solvus solution heat treatment. The material had an equiaxed grain structure （ASTM 6.5-7.5）. The γ precipitates in as-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were MC type and precipitated at grain boundaries. The prior particle boundaries （PPB） in the material originated mainly from γ＇ phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The as-HIP FGH 95 blade retainers showed high strength at room temperature and 650 ℃, excellent creep resistance and outstanding stress rupture strength at 650 ℃.展开更多
The physical characteristics of Ni based superalloy powder with different particle sizes produced by plasma rotation electrode process (PREP) and the microstructure and mechanical properties of P/M superalloy product...The physical characteristics of Ni based superalloy powder with different particle sizes produced by plasma rotation electrode process (PREP) and the microstructure and mechanical properties of P/M superalloy products were investigated. The experimental results show that the optimum powder particle sizes should be in the range of 50-100 μm or 50-150 μm, which can reduce production cost, simplify process and guarantee P/M product quality.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52175319 and 52090043)the Fundamental Research Funds for the Central Universities(No.YCJJ202202003)the National Science and Technology Major Project(No.2017-Ⅵ-0009-0080).
文摘Isothermal forging(IF)is an effective method for forming difficult-to-deform materials like P/M superalloys.Understanding the isothermal compression microstructural evolution mechanism of a novel P/M s-peralloy provides the basis for its optimized IF planning.In this study,the isothermal compression tests of a novel fine-grained P/M nickel-based superalloy were carried out at 1000-1150℃with strain rates of 0.001-0.01 s^(−1).The results indicated that the alloy exhibits three distinct flow characteristics:continuous softening after reaching the peak stress,near-steady superplastic flow,and discontinuous hardening,corresponding to different strain rate sensitivity exponent(m)values.Varied microstructural evolution mechanisms,including grain boundary sliding(GBS),dynamic recrystallization(DRX),and grain growth,are dominated in different m-value domains.Meanwhile,different roles of primaryγ’play in microstruc-tural evolution were clarified.A moderate fraction of primaryγ’with 8.5%-14.2%can well coordinate the GBS and hinder excessive grain growth at a high m value domain(m>0.4).When 0.2<m<0.4,the role of the primaryγ’is changed to promote dislocation accumulation,accelerating the nucleation of DRXed grains.As the primaryγ’is dissolved at 1150℃,obvious grain growth was observed after compression.Work hardening effect by overgrown grains competed with DRX softening results in the discontinuous rising stress.
文摘FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process （PREP）, hot isostatic pressing （HIP） at super-solvus temperature and a sub-solvus solution heat treatment. The material had an equiaxed grain structure （ASTM 6.5-7.5）. The γ precipitates in as-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were MC type and precipitated at grain boundaries. The prior particle boundaries （PPB） in the material originated mainly from γ＇ phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The as-HIP FGH 95 blade retainers showed high strength at room temperature and 650 ℃, excellent creep resistance and outstanding stress rupture strength at 650 ℃.
基金Item Sponsored by Provincal Natural Science Foundation of Shandong of China(Y99F01)
文摘The physical characteristics of Ni based superalloy powder with different particle sizes produced by plasma rotation electrode process (PREP) and the microstructure and mechanical properties of P/M superalloy products were investigated. The experimental results show that the optimum powder particle sizes should be in the range of 50-100 μm or 50-150 μm, which can reduce production cost, simplify process and guarantee P/M product quality.
