Simulation Of Solidification Organization Of 16Cr20Ni14Si2 Investment Casting Based On CAFE Method

The solidification process of metals is so rapid and opaque that it is almost impossible to accurately describe it by direct observation.Researchers and technicians usually use their previous engineering experience to design the casting process parameters,which is inaccurate and a waste of money and time.The Cellular Automata-Finite Element(CAFE)method can visually analyze the solidification process of metals and provide a reference for the selection of process parameters.Although the simulation results of solidification of different alloys based on CAFE method at home and abroad are in good agreement with the actual results,the simulation of solidification of 16Cr20Ni14Si2 high-temperature resistant steel,which is widely used in the aerospace and military industries,is very rare and needs to be studied urgently.In this paper,a CAFE mathematical model for 16Cr20Ni14Si2 alloy was firstly constructed,and then the microscopic solidification organization of a simple cylindrical specimen of16Cr20Ni14Si2 alloy was simulated based on the CAFE method,and the effect of the change of the important process parameters in the investment casting on the microscopic solidification organization of 16Cr20Ni14Si2 alloy was investigated.After that,the optimum process parameters obtained in the specimen were used to design the casting system for the complex thinwalled engine joint housing parts.Then,the applicability of the CAFE method for the 3D solid model was verified through the simulation and analysis of the kernel parameters,and the suitable holding time was designed based on the method.Finally,a casting test was conducted and it was found that the error between the grain size of the castings designed based on the CAFE method and the actual grain size was only 0.07%,which verified the correctness of the CAFE method for the microscopic solidification organization of 16Cr20Ni14Si2 alloy under the investment casting process from the perspective of grain size.To summarize the effect of each process parameter on the microscopic solidification organization during the melting mold casting of 16Cr20Ni14Si2 high temperature resistant steel based on the CAFE method,the results are as follows:(1)the shell thickness increased from 7mm to 9mm,the thicker the shell thickness,the less the number of grains;the shell temperature decreased from 1203.15 K to 1143.15 K,the higher the shell temperature,the more the number of grains;the pouring temperature decreased from1933.15 K to 1913.15 K,the lower the pouring temperature,the more the number of grains;under the three different cooling methods of air cooling,oil cooling and water cooling,the With the increase of casting speed from 0.5kg/s to 4.5kg/s,the number of grains will gradually become more and the grain orientation will also gradually approach the axial direction of heat flow,but the degree of this change will become smaller and smaller.(2)The increase of nucleation density will make the number of grains more and smaller,the proportion of equiaxed grains will increase,and the larger subcooling degree will be more convenient for nucleation,so that more and smaller equiaxed grains will be obtained;(3)At the same solid solution temperature,the longer the holding time,the larger the grains will be,and it is also found that the change of holding time does not change the morphology of the grains,i.e.,no obvious transformation of columnar and equiaxed crystals will occur.