The forming process of cast steel joint mainly includes the filling process and solidification process of cast steel joint. The filling process of cast steel joint is a process in which high-temperature fluid gradually fills the cavity of cast steel joint through the gate. The flow of liquid metal follows the law of hydrodynamics, which can be described by the law of conservation of momentum, the law of conservation of energy and the continuity equation.
Fluid mass conservation equation (continuity equation):
Where u, V and W are the components of velocity in the X, y and Z directions, ρ Is the density of the metal liquid.
Conservation equation of fluid momentum (N-S equation):
Where u, V and W are the components of velocity in the X, y and Z directions, ρ Is the density of the metal liquid, P is the pressure per unit density, μ Is the dynamic viscosity of the fluid.
Fluid energy conservation equation:
Where s is the internal heat source, C is the specific heat capacity, λ Is the thermal conductivity.
The solidification process of cast steel joints is essentially a heat exchange process between heat. Heat exchange mainly includes three processes: heat conduction, heat convection and heat radiation. Heat conduction refers to the process that objects conduct heat from the high-temperature end to the low-temperature end, or the heat exchange process between objects in direct contact with each other is called heat conduction. Pure heat conduction can only occur in solids. Heat convection refers to the heat transfer caused by the relative displacement of each part of the fluid caused by the uneven density of the cold and hot parts in the fluid. Often, heat convection is accompanied by heat conduction. Thermal radiation is a process in which high-temperature substances transfer heat to low-temperature substances through electromagnetic waves.
The simulation of solidification process includes the heat conduction of cast steel joint and sand box, the heat convection between cast steel joint and air, and the heat radiation of liquid in cast steel joint.