A discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels was described. Parametric dislocation dynamics(PDD) simulation of the interaction between an edge dis...A discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels was described. Parametric dislocation dynamics(PDD) simulation of the interaction between an edge dislocation and randomly distributed spherical dispersoids(Y2O3) in bcc iron was performed for measuring the influence of the dispersoid distribution on the critical resolved shear stress(CRSS). The dispersoid distribution was made using a method mimicking the Ostwald growth mechanism. Then, an edge dislocation was introduced, and was moved under a constant shear stress condition. The CRSS was extracted from the result of dislocation velocity under constant shear stress using the mobility(linear) relationship between the shear stress and the dislocation velocity. The results suggest that the dispersoid distribution gives a significant influence to the CRSS, and the influence of dislocation dipole, which forms just before finishing up the Orowan looping mechanism, is substantial in determining the CRSS, especially for the interaction with small dispersoids. Therefore, the well-known Orowan equation for determining the CRSS cannot give an accurate estimation, because the influence of the dislocation dipole in the process of the Orowan looping mechanism is not accounted for in the equation.展开更多
To develop advanced high speed steel with high vanadium content,a kind of vanadium content 9% high speed steel in the form of circular ring was spray formed under certain thermal conditions.The carbides topography of ...To develop advanced high speed steel with high vanadium content,a kind of vanadium content 9% high speed steel in the form of circular ring was spray formed under certain thermal conditions.The carbides topography of as-cast and as-sprayed 9V steel were observed.The effects of post thermo-mechanical processing（hot isostatic pressing and hot forging） and heat treatment on the microstructure and carbides distribution were investigated.The spray formed 9V steel typically consists of fine,homogeneous and angular-shaped MC carbides with diameters ranging from 1 to 2 μm.Spray formed 9V steel shows an excellent hot workability following increase of forging ratio due to fine homogeneous carbides.After heat treatment,spray formed 9V steel is composed of MC carbides,martensite and retained austenite.The hardness value of heat treated materials is inversely proportional to the volume fraction of residual austenite.Fine dispersed MC carbides have significant influences on the dislocation motion of spray formed 9V steel.展开更多
文摘A discrete dislocation plasticity analysis of dispersion strengthening in oxide dispersion strengthened(ODS) steels was described. Parametric dislocation dynamics(PDD) simulation of the interaction between an edge dislocation and randomly distributed spherical dispersoids(Y2O3) in bcc iron was performed for measuring the influence of the dispersoid distribution on the critical resolved shear stress(CRSS). The dispersoid distribution was made using a method mimicking the Ostwald growth mechanism. Then, an edge dislocation was introduced, and was moved under a constant shear stress condition. The CRSS was extracted from the result of dislocation velocity under constant shear stress using the mobility(linear) relationship between the shear stress and the dislocation velocity. The results suggest that the dispersoid distribution gives a significant influence to the CRSS, and the influence of dislocation dipole, which forms just before finishing up the Orowan looping mechanism, is substantial in determining the CRSS, especially for the interaction with small dispersoids. Therefore, the well-known Orowan equation for determining the CRSS cannot give an accurate estimation, because the influence of the dislocation dipole in the process of the Orowan looping mechanism is not accounted for in the equation.
基金Funded by the National Natural Science Foundation of China(No.51301143)the National Postdoctoral Fundation of China(No.2014M560727)+1 种基金the Science and Technology Innovation Project of SWJTU University(No.2682014CX001)the Sichuan Province Science and Technology Support Program(CN)(No.2015GZ0228)
文摘To develop advanced high speed steel with high vanadium content,a kind of vanadium content 9% high speed steel in the form of circular ring was spray formed under certain thermal conditions.The carbides topography of as-cast and as-sprayed 9V steel were observed.The effects of post thermo-mechanical processing（hot isostatic pressing and hot forging） and heat treatment on the microstructure and carbides distribution were investigated.The spray formed 9V steel typically consists of fine,homogeneous and angular-shaped MC carbides with diameters ranging from 1 to 2 μm.Spray formed 9V steel shows an excellent hot workability following increase of forging ratio due to fine homogeneous carbides.After heat treatment,spray formed 9V steel is composed of MC carbides,martensite and retained austenite.The hardness value of heat treated materials is inversely proportional to the volume fraction of residual austenite.Fine dispersed MC carbides have significant influences on the dislocation motion of spray formed 9V steel.
