Influence of Thermophysical Characteristics of Alloy and Mold Material on Casting Solidification Rate

Obtaining castings of a given quality is the main task of foundry production. One of the stages of casting technology is melt solidification in the mold. When studying the casting solidification process, it is necessary to fully consider all the features of heat transfer between casting and mold. The influence of various thermophysical parameters of alloy and mold material on casting formation is considered. In the analysis, original mathematical models were used to calculate the coefficient and time of complete casting solidification in sand-clay and metal forms. These models consider geometric parameters of casting, main thermophysical parameters of casting metal and mold material, heat transfer conditions at crystallization front, on casting-mold boundary and on the mold surface. The analysis of time dependence and casting solidification rate on thermophysical parameters (heat capacity, density, heat conductivity of casting material and mold, specific heat of metal crystallization) was carried out. The storage capacity and heat storage process are fully characterized by the value of heat storage coefficient. This coefficient practically determines the rate of heat loss by the casting which plays a decisive role in its properties forming. Therefore, this parameter is selected for a comprehensive analysis of thermal processes occurring in casting and mold. The influence of thickness and thermal conductivity of the chill paint layer on casting solidification in metal molds is considered. The basic calculation formulas and initial data are presented. Calculations were carried out for castings of the following types: endless plate, endless cylinder, and ball. The simulation results of solidification process parameters are presented in graphic form. Using various alloys as an example, it has been shown by calculations that it is possible to change time and speed of alloy solidification in a wide range when changing the composition and properties of mold material. In this case, the processes for forming the structure and properties of castings are controlled.