The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experime...The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experimental results show that the solid particles obtained with self-inoculation method are in smaller grain size and globular shape after partial remelting, compared with those prepared with other casting methods. In the optimized process conditions, the average size of solid particles of partially remelted billet is 65 μm, and the shape factor is 1.12. The process parameters, i.e. pouting temperature, addition amount of self-inoculants, and the slope angle of multi-stream mixing cooling chalmel have influence on the microstructure of partially remelted billet. The optimized temperature is from 680 ℃ to 700 ℃, addition amount of self-inoculants is between 5% and 7% （mass fraction）, slope angle of multi-stream mixing cooling channel is between 30° and 45°, with which the dendritic microstructure of as-cast billet can be avoided, and the size of solid particles ofremelted billet is reduced.展开更多
In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding ...In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.展开更多
基金Project(2007CB613700) supported by the National Basic Research Program of ChinaProject(50964010) supported by the National Natural Science Foundation of ChinaProject(090WCGA894) supported by the International S&T Cooperation Program of Gansu Province,China
文摘The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experimental results show that the solid particles obtained with self-inoculation method are in smaller grain size and globular shape after partial remelting, compared with those prepared with other casting methods. In the optimized process conditions, the average size of solid particles of partially remelted billet is 65 μm, and the shape factor is 1.12. The process parameters, i.e. pouting temperature, addition amount of self-inoculants, and the slope angle of multi-stream mixing cooling chalmel have influence on the microstructure of partially remelted billet. The optimized temperature is from 680 ℃ to 700 ℃, addition amount of self-inoculants is between 5% and 7% （mass fraction）, slope angle of multi-stream mixing cooling channel is between 30° and 45°, with which the dendritic microstructure of as-cast billet can be avoided, and the size of solid particles ofremelted billet is reduced.
基金support rendered through a Major Research Project No. F-31-51/2005(SR)
文摘In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.
