A Study Of The Squeeze Casting Process Of The Steel Parts With Semi-closed Cavity

Aiming at the problem of high cost and low productivity in forming complex internal steel parts,In this paper,the technical route of steel parts with complex structure formed by squeeze casting is proposed.The following three problems are mainly studied.Firstly,The structural analysis of steel piston in typical parts of semi-closed cavity is carried out,the special mould for squeeze casting and the optimization of the mold structure and process parameters by numerical simulation is also designed.Secondly,the microsturcture and tensile strength of 12CrMnMo under different squeeze pressure was studied.Finally,a special soluble core for semi-closed cavity of squeeze casting is developed.The study of semi-closed cavity steel is studied with steel piston.Using ProCAST to simulate the process,it provided the design of squeeze casting steel piston blank drawing,squeeze casting method,mold design scheme,process parameters and technical process.Using and ANSYS to check and verify the complicated parts,the results showed that the squeeze casting steel piston forming scheme could meet the requirements of complete molding.The influence of the squeeze pressure on the microstructure and properties of the 12CrMnMo alloy steel was demonstrated by comparing different ratios of squeeze casting.With the increase of the squeeze pressure,the ferrite grain sizes in the castings of 12CrMnMo were reduced.When the squeeze pressure increased to 150MPa,the microstructure began to be transformed from ferrite and pearlite into striated bainite and acicular ferrite.When it was 180MPa,the grain size difference between different positions decreases and tended to be uniform.The study on the structure and properties of 12CrMnMo in heat treatment showed that the distribution of squeeze casting was more uniform after annealing,and the comprehensive mechanical properties were better.In the same heat treatment phase,the number of dimples increased as the pressure increased,and the plastic deformation capacity of the alloy also increased.The soluble core of semi-closed cavity of liquid die forging is made of NaAlO2,which is a base body refractory,with NaH2PO4,bentonite and water as binder.The results showed that the wet compressive strength of the soluble core was large,reaching up to 0.128MPa.After the content of bentonite was over 10%,the wet compressive strength of the soluble core decreased with the increase of bentonite content.The dry strength of soluble core after drying was changed with the content of NaH2PO4.When the content of NaH2PO4 was certain,the dry strength of soluble core decreased with the increase of bentonite content.The surface quality increased with the increase of NaH2PO4 content,the surface roughness increased.When the content of NaAlO2 was over 60%,the line shrinkage rate of soluble core was gradually smaller and tended to be stable.Combined with the above studies,the proportion is 10%of bentonite,NaH2PO430%,NaAlO260%,and the soluble core of water is adequate to satisfy the requirement of liquid die-forming of semi-closed cavity steel.