The effects of different contents of vanadium(V)(0.1,0.2,and 0.3 wt%)on the microstructure evolution and mechanical properties of 718H steel were investigated.The precipitate was characterized by means of atom probe t...The effects of different contents of vanadium(V)(0.1,0.2,and 0.3 wt%)on the microstructure evolution and mechanical properties of 718H steel were investigated.The precipitate was characterized by means of atom probe tomography(APT)and bright-field transmission electron microscopy(TEM).The increase in V content has great benefits for strength,but has an adverse effect on impact toughness.The strength increase can be attributed to the influence of V addition on dislocation density,misorientation gradient,and fine scale MC precipitates.Precipitation strengthening mainly contributes to the V-added steel by analyzing various strengthening mechanisms.However,fine scale MC precipitates can pin dislocation leading to a decrease in its mobility.A large number of immovable dislocations will increase the dislocation accumulation,internal stress and brittle cracking,resulting in a gradual decrease in impact toughness with the V addition.In addition,compared with V-free steel,the dissolved V content in austenite decreases the grain boundary energy and inhibits the diffusion of the C atoms,ultimately reducing the transformation range of pearlite(P).展开更多
基金financially supported by the National Key Research and Development Program of China (No. 2016YFB0300401)supported by Cooperation Program of Hubei province and Chinese Academy of Sciences (The Research and Development of Key Technologies for Special Steel of Homogeneous High Performance)
文摘The effects of different contents of vanadium(V)(0.1,0.2,and 0.3 wt%)on the microstructure evolution and mechanical properties of 718H steel were investigated.The precipitate was characterized by means of atom probe tomography(APT)and bright-field transmission electron microscopy(TEM).The increase in V content has great benefits for strength,but has an adverse effect on impact toughness.The strength increase can be attributed to the influence of V addition on dislocation density,misorientation gradient,and fine scale MC precipitates.Precipitation strengthening mainly contributes to the V-added steel by analyzing various strengthening mechanisms.However,fine scale MC precipitates can pin dislocation leading to a decrease in its mobility.A large number of immovable dislocations will increase the dislocation accumulation,internal stress and brittle cracking,resulting in a gradual decrease in impact toughness with the V addition.In addition,compared with V-free steel,the dissolved V content in austenite decreases the grain boundary energy and inhibits the diffusion of the C atoms,ultimately reducing the transformation range of pearlite(P).
