Effect of vanadium micro-alloying on the microstructure evolution and mechanical properties of 718H pre-hardened mold steel
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2019年第11期
论文作者：Hanghang Liu Paixian Fu Hongwei Liu Chen Sun Ningyu Du Dianzhong Li
文章页码：2526 - 2536
摘 要：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）.
Hanghang Liu1,2,3，Paixian Fu1,3，Hongwei Liu1,3，Chen Sun1,2,3，Ningyu Du1,2,3，Dianzhong Li1,3
1. Institute of Metal Research,Chinese Academy of Sciences2. School of Materials Science and Engineering,University of Science and Technology of China3. Shenyang National Laboratory for Materials Science
摘 要：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）.
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