The FDM numerical simulation software,ViewCast system,was employed to simulate the low pressure die casting(LPDC)of an aluminum wheel.By analyzing the mold-filling and solidification stage of the LPDC process,the dist...The FDM numerical simulation software,ViewCast system,was employed to simulate the low pressure die casting(LPDC)of an aluminum wheel.By analyzing the mold-filling and solidification stage of the LPDC process,the distribution of liquid fraction,temperature field and solidification pattern of castings were studied.The potential shrinkage defects were predicted to be formed at the rim/spoke junctions,which is in consistence with the X-ray detection result.The distribution pattern of the defects has also been studied.A solution towards reducing such defects has been presented.The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold.Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.展开更多
The microstructure, precipitate type, precipitate distribution and tensile strength of a ZL205 alloy, beforeand after ageing treatment, have been studied by means of optical microscopy and transmission electron micros...The microstructure, precipitate type, precipitate distribution and tensile strength of a ZL205 alloy, beforeand after ageing treatment, have been studied by means of optical microscopy and transmission electron microscopy.The results showed that the as-cast microstructure of the alloy was made up of α-Al and eutectic phase distributedat the grain boundaries. During ageing treatment, the tensile strength increased at first and then reduced with time,and the highest ultimate tensile strength was found to be around 488.2 MPa.展开更多
The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high therma...The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth.For dendritic structures formed under a high thermal gradient,the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth condition.Furthermore,it has been observed that,with increasing pulling velocity,there exists a cell/dendrite transition region consisting of cells and dendrites,which varies with the thermal gradient in a contradicting way,i.e.increase of the thermal gradient leading to the decrease of the range of the transition region.The simulations agree reasonably well with experiment results.展开更多
基金funded by the Innovation Fund for Outstanding Scholar of Henan Province(No.0621000700)
文摘The FDM numerical simulation software,ViewCast system,was employed to simulate the low pressure die casting(LPDC)of an aluminum wheel.By analyzing the mold-filling and solidification stage of the LPDC process,the distribution of liquid fraction,temperature field and solidification pattern of castings were studied.The potential shrinkage defects were predicted to be formed at the rim/spoke junctions,which is in consistence with the X-ray detection result.The distribution pattern of the defects has also been studied.A solution towards reducing such defects has been presented.The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold.Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.
文摘The microstructure, precipitate type, precipitate distribution and tensile strength of a ZL205 alloy, beforeand after ageing treatment, have been studied by means of optical microscopy and transmission electron microscopy.The results showed that the as-cast microstructure of the alloy was made up of α-Al and eutectic phase distributedat the grain boundaries. During ageing treatment, the tensile strength increased at first and then reduced with time,and the highest ultimate tensile strength was found to be around 488.2 MPa.
文摘The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth.For dendritic structures formed under a high thermal gradient,the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth condition.Furthermore,it has been observed that,with increasing pulling velocity,there exists a cell/dendrite transition region consisting of cells and dendrites,which varies with the thermal gradient in a contradicting way,i.e.increase of the thermal gradient leading to the decrease of the range of the transition region.The simulations agree reasonably well with experiment results.
