Archives of Metallurgy and Materials

Abstract

Influence of lIquId Metal MoveMents on the castIng creatIon knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.

Numerical Evaluation of the Impact of Selected Physical Phenomena and Riser Shape on the Formation of Shrinkage Defects in the Casting-Riser System

“…The mathematical model of the casting solidification process considering the liquid metal movements (complex model) is based on the solution of the following system of equations in a cylindrical axial-symmetric coordinate system [2][3][4][5][6][7]:…”

“…The equations ( 1)-( 4) are completed by appropriate boundary conditions and initial conditions. The initial conditions for temperature and velocity fields are given, respectively, as [3][4][5] The boundary conditions, specified in the considered problem, on the indicated surfaces (Fig. 1) were as follows:…”

“…-for temperature [3][4][5][6], This task was solved using the finite element method (FEM) in the weighted residuals formulation [3][4][5].…”

“…One of such defects is the formation of shrinkage cavities, which cannot be completely avoided, but the heat transport process can be controlled so as to reduce these defects by moving their location to the riser. Research on real objects is much more difficult, which is why computer simulations are becoming the basic method of controlling the casting solidification process [1][2][3][4][5][6][7]. In this paper, the course of the solidification process is analysed in the cylindrical or conical-shaped casting-riser system using a basic or complex model.…”

“…In this paper, the course of the solidification process is analysed in the cylindrical or conical-shaped casting-riser system using a basic or complex model. In the complex model [2,3,5,6], the mutual influence of thermal and flow phenomena was taken into account, starting from the moment of filling the metal mould with molten metal and ending with complete solidification of the casting. For comparison, the solidification process of the casting was analysed using the basic model [4], in which only thermal phenomena are taken into account.…”