Process modeling and parameter setting of nodular cast iron for hub support

(1) Material definition

The material used in the simulated automobile hub support is the high strength and Toughness Nodular Cast Iron designed in Chapter 3. Because it is not the existing national standard nodular cast iron, and there is no relevant material physical parameter data in the magma software, the physical parameter database of the high strength and Toughness Nodular Cast iron is customized according to the chemical composition and measured mechanical properties determined in Chapter 3. The solidus temperature of the material is 1166 ℃, and the liquidus temperature is 1169 ℃.

(2) Definition of heat transfer coefficient

The casting material is nodular cast iron and the sand mold material is quartz sand. According to the classification of heat transfer coefficient in magma software and combined with practical experience, the heat transfer coefficient between sand mold and casting, sand core and nodular cast iron is set as “tempiron”. This group of heat transfer coefficients change with the change of temperature during pouring (as shown in the figure), which can better reflect the actual heat transfer situation.

(3) Boundary condition definition

The nodular cast iron of the hub support studied is ordinary sand casting, so the boundary condition is defined as the default mode in the grouping of heat convection and radiation, that is, the boundary condition depends on the temperature of the sand cavity.

(4) Filling definition

The nodular cast iron of automobile hub support is produced by traditional gravity casting, so the filling direction is selected along the – Z direction, and the time is used as the filling basis. According to the calculation results in subsection 4.3.6 above, the filling time is set as 8 s; By consulting the data and combining with the actual production experience, the pouring temperature is selected in the range of 1370 ~ 1425 ℃, and the lower pouring temperature is generally preferred. Therefore, the initial pouring temperature is set to 1370 ℃. Solver 4 solution method is adopted, and the data storage frequency is once every 2%.

(5) Solidification setting

In the simulation process, the temperature mode is selected as the basis for stopping the calculation. The temperature is set as the material solidus temperature of 1166 ℃, that is, the solidification process calculation starts when the temperature drops below this temperature, and the data storage frequency is stored every 5%.