1. Current situation
Material physical parameters are the direct basis of digital casting, which play a decisive role in the accuracy and reliability of modeling and numerical simulation results. At present, the material performance parameters applied in the numerical simulation of casting process can be divided into performance parameters for mold filling and solidification simulation, mechanical performance parameters for thermal stress analysis and performance parameters for microstructure simulation . Specifically, the physical parameters used in the simulation of the casting process include: physical parameters of the material itself, such as density, etc.; thermal physical parameters related to heat transfer, such as thermal conductivity, specific heat, enthalpy (latent heat of crystallization), etc.; parameters related to shrinkage, such as volume shrinkage coefficient and linear shrinkage coefficient; parameters related to liquid flow, such as viscosity, surface tension, etc.; parameters related to mechanical properties, etc, For example, Young’s modulus of elasticity, shear modulus of elasticity, plastic hardening modulus, Poisson’s ratio, yield stress, fracture stress, etc.; parameters related to structure change, such as phase change temperature, solute diffusion coefficient, phase diagram, etc.; parameters related to electromagnetic, such as conductivity, etc.
The casting process involves many kinds of materials, such as metal materials, molding / core making materials, coatings and so on, which are essentially different. These materials include both metal and nonmetal, solid materials, bulk materials and liquid materials. In the process of casting, the temperature and state of castings, molds or auxiliary materials change greatly. The material parameters are also related to the simulation scale. For example, the elastic modulus of some materials can be considered to be isotropic in the macro scale, while in the meso scale, it shows obvious anisotropy . In addition, with the deepening of simulation calculation, involving the coupling of multi-scale and multi physical phenomena, the accuracy requirements continue to improve, so the material performance parameters and the knowledge of the inherent characteristics of materials can not meet the needs of casting process solidification simulation, and even hinder the further development of simulation. However, it is still very difficult to obtain accurate and complete physical parameters, which is one of the important factors affecting the digitization of the casting process.
In order to develop the digital casting technology and integrate the process design to ensure the casting quality and life prediction, it is urgent to establish a standardized database of key material properties, which is used to store the relationship between processing technology and microstructure, the information of microstructure, the relationship between microstructure and material performance, etc., to support the development and verification of the calculation model.
In China, the relevant supporting foundation of digital casting is weak, for example, there is no special database, no material data thermodynamics calculation software, which is completely blank in this aspect, and completely relies on foreign software such as jmat pro, thermo Calc, pandat, etc. Generally, the performance parameters of materials can be found in various manuals and articles, but they are often incomplete. At the same time, the values of the same parameter from different sources sometimes differ greatly, even contradict each other. Therefore, how to collect and sort out these parameters and carry out reliability verification is very important. The reliability of data can be checked by comparing similar materials. The physical parameters of casting materials can be obtained by experiment and calculation, literature retrieval and verification, and the data sharing, retrieval and reference can be realized by database technology, which lays a solid foundation for digital casting.
(1) Target to be achieved by 2020:
A standardized classification method of foundry process information is established, and an open database of foundry materials is established based on it.
(2) Target to be achieved by 2025:
An advanced experimental platform is established to provide technical support for obtaining accurate material property parameters and experimental verification platform for digital casting technology.
(3) Target to be achieved by 2030:
By using information technology to study the internal relationship between different physical quantities of materials, a perfect database of casting digital, network and intelligent application is established, which is open to the casting industry in an all-round way.