Numerical Simulation Optimization And Verification Of Casting Process For 16Cr20Ni14Si2 Connecting Pipe Shell

As a component for diesel engines,the connection tube housing needs to work in high temperature and high pressure environment for a long time.In order to meet the requirements of use,high temperature resistant alloy materials are usually selected and molded by investment casting.However,the connection tube shell is a thin-walled shell casting with uneven wall thickness,which is easy to produce defects such as shrinkage and shrinkage holes and thermal cracks during the casting process.In addition,the requirement for high dimensional accuracy and good overall performance of the casting leads to high casting difficulty and low yield rate.In order to improve the yield of such products,this study selected 16Cr20Ni14Si2 high temperature stainless steel as the casting material,using simulation software,the casting process of alloy liquid filling,solidification and stress field simulation of the whole process,the casting process may appear shrinkage shrinkage,thermal cracking and other defects to analyze the prediction,and process optimization,the trial production of the connection tube to meet the technical requirements The process optimization was carried out,and the connection tube shell casting was produced to meet the technical requirements,which improved the qualification rate and reduced the cost,and has certain engineering application value.Firstly,the theoretical model involved in the process of filling and solidification of the connecting tube shell casting is introduced,and the material database of 16Cr20Ni14Si2 stainless steel is established by using Pro CAST software,and according to the dimensional and structural characteristics of the casting,the top-filling pouring method is adopted,and the gate cup capacity shrinkage method is combined with the gate introduction position to design and optimize the casting of the connecting tube shell.Secondly,the simulation results were used to predict the defects and optimize the pouring process;finally,in order to verify the simulation results and ensure the quality of the casting,the casting of the connecting tube shell was tested and inspected,and the heat treatment experiment was designed to study the effect of heat treatment process on the mechanical and properties of the casting.The results were obtained as follows:(1)Based on ProCAST software,the initial casting scheme simulation analysis of the connecting tube shell casting shows that: a small amount of shrinkage and shrinkage defects appear at the thin wall of the casting and at the side of the transition,and the effective stress at the end of solidification is lower than the yield limit.The orthogonal experiment was designed to experimentally optimize the three parameters of pouring temperature,shell preheating temperature and pouring speed.Through the extreme difference analysis,it was obtained that: the pouring speed has the greatest influence on the defects of the casting during the casting of the connecting tube shell,the shell preheating temperature is the second and the pouring temperature is the smallest;the optimal pouring process parameters were determined as follows: the pouring temperature is 1640 ℃,the shell preheating temperature is 1000 ℃ and the pouring speed is The optimized defect prediction results show that there is no shrinkage and shrinkage hole defects inside the casting and the tendency of thermal cracking is low.(2)Using the mold to press the wax pattern,using silica-sol shell making process to prepare the shell,melting and pouring,after removing the shell,surface treatment and other methods to obtain the casting,and then the casting quality inspection,the dimensional inspection results show that the casting surface quality is good,the dimensional accuracy is within the tolerance of the drawing requirements,industrial CT inspection shows that there are no obvious defects inside the casting,in line with the numerical simulation prediction results.(3)By testing the mechanical properties of the same furnace test bar,it was found that the mechanical properties of the casting meet the technical requirements;At the same time,the casting samples were subjected to solution treatment and hardness testing,and the results showed that the hardness of the samples reached its highest under solution treatment at 1130 ℃.The mechanical and properties of the sample meet the technical requirements of the casting.