T122 steel has been used to produce superheater or reheater of ultra supercritical boilers. With the help of chemical phase extraction and mierostructure characterization, the performance of aging precipitates of T122...T122 steel has been used to produce superheater or reheater of ultra supercritical boilers. With the help of chemical phase extraction and mierostructure characterization, the performance of aging precipitates of T122 steel, such as M23C6 carbide, Laves phase and MX phase was investigated, the strengthening mechanism of the steel was discussed, and the thermal yield stress of lath substructure, dislocations and precipitates of the steel were calculated. It was found that lath substructure and dislocations dominated the strengthening attribution and precipitation hardening went second to the strengthening attribution.展开更多
Based on dislocation reaction theory and Avrami equation, a constitutive equation model was developed to describe dynamic recovery and dynamic recrystallization during hot deformation of T122 heat resistant steel, whi...Based on dislocation reaction theory and Avrami equation, a constitutive equation model was developed to describe dynamic recovery and dynamic recrystallization during hot deformation of T122 heat resistant steel, which have taken the effect of dynamic strain aging into account. Uniaxial hot compression test had been carried out over a wide range of strain rate （0.01 to 10 s-1 ） and temperature （900 to 1 200 ~C） with the help of Gleeble 3500. Obtained experimental data was applied to determine the material parameters in proposed constitutive equations of T122 steel, by using the non-linear least square regress optimization method. The calculated constitutive equations are quantita- tively in good agreement with experimentally measured curves and microstructure observation. It shows that propose constitutive equation T122 steel is able to be used to predict flow stress of T122 steel during hot deformation in aus- tenite temperature scope.展开更多
11Cr-0.4Mo-2W-CuVNb steel （ASME Gr.122） is used for boiler components in ultra- supercritical （USC） thermal power plants. The creep strength of high-Cr steel welds decreases due to the formation of Type IV creep d...11Cr-0.4Mo-2W-CuVNb steel （ASME Gr.122） is used for boiler components in ultra- supercritical （USC） thermal power plants. The creep strength of high-Cr steel welds decreases due to the formation of Type IV creep damage in the heat-affected zone （HAZ） during long-term use at high temperatures. In the present study, the processes and mechanisms of Type Ⅳ creep damage were elucidated by investigating the long-term creep strength, microstructure and damage behavior of Gr.122 steel welds. Creep tests using thick welded joints were interrupted at several time steps, and the initiation, evolution and distribution of creep damage were measured. It was found that the formation and growth of creep damage was suppressed during the steady- state stage; creep voids formed at 0.5 of life, and coalesced to form a crack after 0.9 of life. Type IV creep damage was mostly observed in the area about 30% below the surface of the plate. Differences in creep damage behavior between Gr.122 and Gr.91 steel welds were examined. Experimental creep damage distribution was compared with computed versions using the finite element method and damage mechanics.展开更多
基金Item Sponsored by National Hi-Tech Research and Development Program of China (863 program) (2006AA03Z513)
文摘T122 steel has been used to produce superheater or reheater of ultra supercritical boilers. With the help of chemical phase extraction and mierostructure characterization, the performance of aging precipitates of T122 steel, such as M23C6 carbide, Laves phase and MX phase was investigated, the strengthening mechanism of the steel was discussed, and the thermal yield stress of lath substructure, dislocations and precipitates of the steel were calculated. It was found that lath substructure and dislocations dominated the strengthening attribution and precipitation hardening went second to the strengthening attribution.
基金Sponsored by National High-Tech Research and Development Program (863Program) of China (2003AA331060)
文摘Based on dislocation reaction theory and Avrami equation, a constitutive equation model was developed to describe dynamic recovery and dynamic recrystallization during hot deformation of T122 heat resistant steel, which have taken the effect of dynamic strain aging into account. Uniaxial hot compression test had been carried out over a wide range of strain rate （0.01 to 10 s-1 ） and temperature （900 to 1 200 ~C） with the help of Gleeble 3500. Obtained experimental data was applied to determine the material parameters in proposed constitutive equations of T122 steel, by using the non-linear least square regress optimization method. The calculated constitutive equations are quantita- tively in good agreement with experimentally measured curves and microstructure observation. It shows that propose constitutive equation T122 steel is able to be used to predict flow stress of T122 steel during hot deformation in aus- tenite temperature scope.
文摘11Cr-0.4Mo-2W-CuVNb steel （ASME Gr.122） is used for boiler components in ultra- supercritical （USC） thermal power plants. The creep strength of high-Cr steel welds decreases due to the formation of Type IV creep damage in the heat-affected zone （HAZ） during long-term use at high temperatures. In the present study, the processes and mechanisms of Type Ⅳ creep damage were elucidated by investigating the long-term creep strength, microstructure and damage behavior of Gr.122 steel welds. Creep tests using thick welded joints were interrupted at several time steps, and the initiation, evolution and distribution of creep damage were measured. It was found that the formation and growth of creep damage was suppressed during the steady- state stage; creep voids formed at 0.5 of life, and coalesced to form a crack after 0.9 of life. Type IV creep damage was mostly observed in the area about 30% below the surface of the plate. Differences in creep damage behavior between Gr.122 and Gr.91 steel welds were examined. Experimental creep damage distribution was compared with computed versions using the finite element method and damage mechanics.
