| Some defects existed in K4169 super-alloy, such as serious microstructure segregation, thick dendrite, big Laves phase, shrinkage and osteoporosis. The stability of alloy's performance can be improved and the alloy can be widely used as if this segregation was reduced, the thick dendrite was changed into small equiaxed grains. Semi-solid forming technology can improve the alloy structure and mechanical properties, reduce the stomata and segregation. the present dissertation investigated the influence of isothermal heat treatment temperature and thermal insulation time on the semi-solid microstructure evolution and mechanical performance of K4169 super-alloy. And investigated influencing factor of microstructure and mechanical performance in the condition of solid solution aging treatment,high-temperature long-term aging and hot corrosion.The main results as follow:(1) The dendritic structure in the casting structure of K4169 super-alloy was transferred into spherical grain structure by semi-solid isothermal heat treatment. The best heat treatment process: heat treatment temperature 1320℃, thermal insulation time 45min. The compress strength of K4169 in the best heat treatment process is higher than casting structure. Compared to casting structure, hardness of semisolid structure decreased.(2) After different solid solution temperature treatment ranged from 950℃to 1100℃, theγ' phase in the semisolid structure of K4169 super-alloy was dissolution with the increasing of solid solution treatment temperature, and harmful intergranular structure was disappeared. Compressive strength and hardness of alloy were decreased with the increasing of solid solution temperature.(3) After different solid solution temperature treatment and aging treatment (720℃,8h+620℃,8h,air-cold),the mechanical performance of alloy were improved. With the increasing of solid solution temperature, the amount ofγ' phase were increased, the size ofγ' phase was thin and well-proportioned, the distribution ofγ' phase was dispersed, the compress intensity and the hardness of alloy semi-solid structure were increased.(4) After solid solution(950℃) + aging treatment and long-term aging treatment (650℃,100h),γ" phase changed into 5 phase; After different solid solution treatment and long term aging treatment, the compress intensity and the hardness of semi-solid structure and casting structure were decreased. After solid solution treatment (1100℃,1h), the mechanical performance of semi-solid structure and casting structure were better.(5) After solid solution(1100℃) +aging treatment and hot corrosion, the lose weight of casting structure and semi-solid structure were almost equal;The composition of corrosion layer were oxide layer and sulfide layer.
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