In order to evaluate the deformation characteristics of spray formed superalloy GH742and determine the appropriate forging procedure of the alloy on this basis, the influenceof deformation temperature and strain rate ...In order to evaluate the deformation characteristics of spray formed superalloy GH742and determine the appropriate forging procedure of the alloy on this basis, the influenceof deformation temperature and strain rate on the ductility of spray formed GH742was investigated by using the Gleeble-3500 thermal-mechanical testing machine. It isshown that the forgeability of spray formed GH742 is better than conventional GH742by ingot metallurgy because of refined grain structure and enhanced chemical homo-geneity of spray formed GH742. In the temperature range of 1020 to 1100℃, theductility of spray formed GH742 is dependent on the deformation temperature and isincreased linearly in proportion to the increment of deformation temperature, whichis more than 40% at 1020℃ and more than 60% at the temperature between 1100and 1140℃. Furthermore, the results indicate the flow stress is affected considerablyby the deformation temperature and strain rate. In the temperature range of 1020 to1140℃, the maximum flow stress of spray formed GH742 increases with the incrementof strain rate and decreases with the increment of the deformation temperature.展开更多
The segregation during solidification and high temperature diffusion during homogenization of niobium in a highly alloyed nickel-base superalloy were investigated.Niobium is seriously segregated into the interdendriti...The segregation during solidification and high temperature diffusion during homogenization of niobium in a highly alloyed nickel-base superalloy were investigated.Niobium is seriously segregated into the interdendritic regions with segregation coefficient as high as 4.30.Various niobium-enriched phases including Laves phase,δ phase,（γ＋γ＇） eutectic,MC and M6C types of carbides precipitated in the interdendritic regions.The soluble temperature of niobium-enriched phases and the degree of dendritic segregation were determined by differential thermal analysis and homogenization treatments at varied temperatures and times.The calculation of elemental diffusion indicates that the diffusion rate of niobium increases remarkably with the homogenization temperature increasing,so that the annealing time can be effectively reduced.A three-step homogenization treatment technology without incipient melting was established to eliminate the segregation of niobium and to obtain a uniform microstructure.展开更多
基金supported by the National Hi-Tech.Research and Development Program of China(No.2002AA336100)
文摘In order to evaluate the deformation characteristics of spray formed superalloy GH742and determine the appropriate forging procedure of the alloy on this basis, the influenceof deformation temperature and strain rate on the ductility of spray formed GH742was investigated by using the Gleeble-3500 thermal-mechanical testing machine. It isshown that the forgeability of spray formed GH742 is better than conventional GH742by ingot metallurgy because of refined grain structure and enhanced chemical homo-geneity of spray formed GH742. In the temperature range of 1020 to 1100℃, theductility of spray formed GH742 is dependent on the deformation temperature and isincreased linearly in proportion to the increment of deformation temperature, whichis more than 40% at 1020℃ and more than 60% at the temperature between 1100and 1140℃. Furthermore, the results indicate the flow stress is affected considerablyby the deformation temperature and strain rate. In the temperature range of 1020 to1140℃, the maximum flow stress of spray formed GH742 increases with the incrementof strain rate and decreases with the increment of the deformation temperature.
文摘The segregation during solidification and high temperature diffusion during homogenization of niobium in a highly alloyed nickel-base superalloy were investigated.Niobium is seriously segregated into the interdendritic regions with segregation coefficient as high as 4.30.Various niobium-enriched phases including Laves phase,δ phase,（γ＋γ＇） eutectic,MC and M6C types of carbides precipitated in the interdendritic regions.The soluble temperature of niobium-enriched phases and the degree of dendritic segregation were determined by differential thermal analysis and homogenization treatments at varied temperatures and times.The calculation of elemental diffusion indicates that the diffusion rate of niobium increases remarkably with the homogenization temperature increasing,so that the annealing time can be effectively reduced.A three-step homogenization treatment technology without incipient melting was established to eliminate the segregation of niobium and to obtain a uniform microstructure.
