Analysis Of Stress And Process Characteristics Of ZM6 Magnesium Alloy Castings

ZM6 magnesium alloy is a material widely used in aerospace materials.The castings used in the aerospace field are mainly complex parts,and the wall thickness mutation structure is common in various types of thin-walled complex components.Due to the difference in solidification time and mechanical obstruction in each part,the wall thickness mutation structure has brought difficulties to the control of the filling and solidification process,resulting in stress concentration in some locations and affecting the service life of castings.At present,the stress of ZM6 magnesium alloy components is not systematically studied,and the basis of process control is lacking.Therefore,this article focuses on the process-based research of ZM6 magnesium alloy casting stress,aiming at the common wall-thickness mutation structure in complex components.The content is as follows:In this paper,the Perzyna model formula in the viscoelastic-plastic mechanical model is transformed,normal temperature and high temperature experiments are designed,and the necessary parameters are calculated by calculating the stress field model according to the experimental results.Using Pro CAST simulation software,thermal stress cracking was simulated using linear elastic,elasto-plastic and visco-elasto-plastic models.The casting experiments were conducted and the simulated data and actual data were compared.The results show that the viscoelastic-plastic mechanical model in ZM6 stress field simulation is more accurate.For the typical wall-thickness structure-I-shaped member,the influence of the casting structure on the stress field was analyzed.The results show that thermal cracking due to the influence of temperature gradient on the riser can be effectively avoided in the area where the wall thickness ratio is controlled between 1/2 and 3/4;the transition structure has better stress on the top and core affected by the riser.Weakened,the stress of the 45° triangular transition structure at the two locations weakened by 37.77% and 54.92%,respectively.The influence of reinforcing rib thickness and cold iron thickness on the stress field in the casting process was analyzed.The results show that: the wall thickness ratio of 1/5 rib setting method will weaken the stress of the interface;the setting of cold iron will increase the stress near the interface of wall thickness abrupt change.However,the thickness of cold iron has little effect on the stress peak.The actual casting was performed.The comparison of the stress values measured by laser speckles and small holes with the simulation results confirmed the influence of the casting process on the stress field.Finally,the change law of the stress before and after the optimization of the casting process in the actual casing components is analyzed.The cold iron placed in the thick wall of the actual casing component increases the interface stress at the wall thickness abrupt change,and the calculated stress value increases by 6.85%.Adding stiffeners to the wall thickness sudden changes in the temperature gradient,the stress value was reduced by 21.8%.The simulation results and the casting process have a good match to the I-shaped stress field.