Numerical Simulation Study On Predicting Phase Composition And Secondary Dendrite Arm Spacing In Aluminum Alloy Casting

Aluminum alloy has excellent casting properties,mechanical properties and physical properties.It is one of the most widely used casting materials at present,and has very critical applications in important fields such as aerospace.The solidification structure of aluminum alloy casting is an important factor affecting its comprehensive performance.Experimental methods such as metallographic observation can only obtain the solidification structure after solidification is completed.It is difficult to directly observe and analyze the change of the casting structure during the solidification process.Numerical simulation technology can intuitively simulate the solidification structure distribution during different stages of solidification,which can effectively guide the design and optimization of the casting process.This paper focuses on the inverse calculation of the thermophysical properties of casting,the prediction of the macrophase composition of aluminum alloy casting,and the prediction of the secondary dendrite arm spacing.The main contents include:(1)Based on the temperature data of the solidification temperature measurement experiment and the numerical simulation temperature field,the accurate thermophysical parameters were obtained through orthogonal experiments of the inverse calculation of the thermophysical parameters.Based on the inversely calculated thermophysical properties parameters,the temperature field of the solidification process in accordance with the actual situation was obtained through numerical simulation.(2)Based on the calculation of material property simulation software JMat Pro,the phase composition database of aluminum alloy was established.Based on the phase composition database and the numerical simulation temperature field,the linear composition of temperature field and the incremental accumulation of phase composition were used to establish a phase composition calculation model for aluminum alloy casting to achieve the prediction of phase composition distribution at different times.(3)Based on the evolution mechanism of the secondary dendrite arm spacing during the solidification process,a calculation model of the secondary dendrite arm spacing of the aluminum alloy casting was established by solving the local solidification time.The distribution of local solidification time and secondary dendrite arm spacing can be predicted.(4)For the solidification process of bearing seat casting and stepped casting,the phase composition calculation program and secondary dendrite arm spacing calculation program were used to predict the distribution of phase composition,local solidification time and secondary dendrite arm spacing.The results of metallographic observation experiments were compared and analyzed,which verified the accuracy and reliability of the prediction program.In this paper,based on the alloy phase composition database and the secondary dendrite arm spacing evolution mechanism during solidification,a phase composition calculation model and a secondary dendrite arm spacing calculation model for aluminum alloy castings are established to realize the prediction of phase composition distribution and secondary dendrite arm spacing distribution during the solidification process.This prediction program can provide effective guidance for the design and improvement of casting process and the evaluation of casting product quality,and has important application value.