.7050 Aluminum Alloy Great Circle Ingots Semi-continuous Casting Process Of Numerical Simulation And The Crack Orientation Analysis

The freezing process of semi-continuous casting was a dynamic process, which referred to the complicated physical changes, including heat transfer, mass transfer, phase change, etc. All kinds of casting defects such as shrinkage porosity, shrinkage cavity, cracking, deformation, etc. were formed in the freezing process. The large scale aluminum ingots with high alloying components were prone to generating crack in the semi-continuous casting process. To study the factors of cracking by using modern numerical simulating technique will redound to find out the controlling and adjusting methods and obtain a good quality ingot without any defects.Firstly, the research developments about high-strength aluminum alloys and the cracking defects as well as its criterions were summarized in this thesis. Also the development and its trends about temperature field and stress field numerical simulation of freezing process were analyzed here. And we established the finite element numerical simulating model of transient temperature field and the elasto-plasticity thermal stress field. Contraposing the lacking of the material parameters about 7050 aluminum alloys in high temperature at present time, as well as the need of our numerical simulating, the author of the thesis measured the corresponding material parameters of 7050 aluminum alloy under high-temperature conditions, and founded its material parameters database.Secondary, a thermal-stress coupling model was established in this thesis basing on the large casting simulation software ProCAST. Also, we defined the complicated boundary conditions, dealed with the freezing latent heat by specifying enthalpy to replace the specific heat and latent heat value, and simulated the freezing process of semi-continuous casting. The sump of the ingot and the distributing regularities of the temperature field and stress field were analyzed and we used the existing cracking criterions to estimate the generating of all kinds of casting cracking. According to the analysis results, a semi-continuous casting technology of avoiding casting cracks was put forward. The study results indicated that the simulating results basically match with the industrial phenomen-ons. The regularities and the conclusions of the thesis can commendably explain the generating conditions of all kinds of cracking defects and be used to guide our industrial produce in a certain extent.