The oxidation behavior of Ni-based superalloy GH4742 exposed to water vapor was investigated at 900-1100℃for 50 h in Ar+20%H_(2)O,with Ar+20%O_(2)included for comparison.The presence of H_(2)O is adverse to formation...The oxidation behavior of Ni-based superalloy GH4742 exposed to water vapor was investigated at 900-1100℃for 50 h in Ar+20%H_(2)O,with Ar+20%O_(2)included for comparison.The presence of H_(2)O is adverse to formation of continuous Cr_(2)O_(3)oxide layer but contributes to generation of big voids.Based on this,Ni^(2+)and Co^(2+)are more easily to diffuse towards the outermost oxide layer(OOL),forming non-protective Ni-and Co-rich oxides with high proportion.This leads to a higher weight gain in Ar+20%H_(2)O than that in Ar+20%O_(2).At elevated temperatures,the spallation of oxide scale occurs while the consumption of Cr is reduced in Ar+20%H_(2)O,and the contents of Ni-and Co-rich oxides at this moment are reduced in the OOL.The oxidation mechanism was also discussed.展开更多
Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasa...Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasad, Gegel, Malas, Murty and Semiatin were compared, and the physical significance of parameters was analyzed. Meanwhile, the processing maps with different instability criteria were obtained. It was shown that instability did not occur when average power dissipation rate was larger than 50% in the temperature range of 1020- 1130℃, corresponding to the strain rate range of 5 × 10-4-3.2 × 10-3 s-1. The domain is appropriate for the processing deformation of superalloy GH4742.展开更多
The temperature changes at the rim,1/2 radius,and bore of the turbine disk during the solution treatment were measured.Based on the measured temperature data,solution treatment experiments with different cooling rates...The temperature changes at the rim,1/2 radius,and bore of the turbine disk during the solution treatment were measured.Based on the measured temperature data,solution treatment experiments with different cooling rates(14,51,and 93℃/min)were performed,and the solution temperatures were 1120 and 1080℃.At all three cooling rates,the multimodal size distribution of γ' precipitates was detected,and the size of γ' precipitates is inversely related to the cooling rate.Only the secondary and tertiary γ' precipitates were found at a solution temperature of 1120℃,and the secondary γ' precipitates progressed from spherical(93 and 51℃/min)to flower-like(14℃/min)shape,with the flower-like γ' precipitates regulated by aggregation.At a solution temperature of 1080℃,the γ' precipitates evolve from cuboids(93 and 51℃/min)to irregular shapes(14℃/min).Irregular γ' precipitates are affected by the lattice mismatch between the matrix and the γ' precipitates.展开更多
基金supported by the National Key R&D Program of China(No.2021YFB3700400)National Natural Science Foundation of China(Nos.52074030,51904021,52174294).
文摘The oxidation behavior of Ni-based superalloy GH4742 exposed to water vapor was investigated at 900-1100℃for 50 h in Ar+20%H_(2)O,with Ar+20%O_(2)included for comparison.The presence of H_(2)O is adverse to formation of continuous Cr_(2)O_(3)oxide layer but contributes to generation of big voids.Based on this,Ni^(2+)and Co^(2+)are more easily to diffuse towards the outermost oxide layer(OOL),forming non-protective Ni-and Co-rich oxides with high proportion.This leads to a higher weight gain in Ar+20%H_(2)O than that in Ar+20%O_(2).At elevated temperatures,the spallation of oxide scale occurs while the consumption of Cr is reduced in Ar+20%H_(2)O,and the contents of Ni-and Co-rich oxides at this moment are reduced in the OOL.The oxidation mechanism was also discussed.
基金supported by the National Key Basic Research Program of China (No. 2010CB631203)
文摘Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasad, Gegel, Malas, Murty and Semiatin were compared, and the physical significance of parameters was analyzed. Meanwhile, the processing maps with different instability criteria were obtained. It was shown that instability did not occur when average power dissipation rate was larger than 50% in the temperature range of 1020- 1130℃, corresponding to the strain rate range of 5 × 10-4-3.2 × 10-3 s-1. The domain is appropriate for the processing deformation of superalloy GH4742.
基金supported by the National Science and Technology Major Project(2017-VI-0018-0090).
文摘The temperature changes at the rim,1/2 radius,and bore of the turbine disk during the solution treatment were measured.Based on the measured temperature data,solution treatment experiments with different cooling rates(14,51,and 93℃/min)were performed,and the solution temperatures were 1120 and 1080℃.At all three cooling rates,the multimodal size distribution of γ' precipitates was detected,and the size of γ' precipitates is inversely related to the cooling rate.Only the secondary and tertiary γ' precipitates were found at a solution temperature of 1120℃,and the secondary γ' precipitates progressed from spherical(93 and 51℃/min)to flower-like(14℃/min)shape,with the flower-like γ' precipitates regulated by aggregation.At a solution temperature of 1080℃,the γ' precipitates evolve from cuboids(93 and 51℃/min)to irregular shapes(14℃/min).Irregular γ' precipitates are affected by the lattice mismatch between the matrix and the γ' precipitates.
