Numerical Simulation And Parameters Optimization Of Reheating Process Of Magnesium Alloys Semi-solid Billets

Semi-solid metal forming technology has been considered to be one of the emerging technologies in metal manufacturing industry in the 21st century. The reheat in semi-solid thixoforming has the significant influence on the semi-solid forming structures of alloy and the following forming quality. So it is very important to research it.So far the numerical simulation of reheating process of magnesium alloy semi-solid billet has been still blank. This thesis use ANSYS finite element software to make single-stage and multi-level electromagnetic induction heating numerical simulation on magnesium alloy semi-solid billet. Simulation process involves heat, magnetic shielding, multi-field coupling and thermal load. ANSYS finite element software has a wide range of applications in structural design and engineering mechanics and has made a very good simulation results. However, in thermal analysis, especially the heat - electromagnetic field simulation, ANSYS finite element software isn't used. So this thesis does a great deal of research in multi-field coupled simulation.In order to ensure the semi-solid billet heating temperature uniformity and cycle time, the multi-stage heating method is raised. The method achieves the heat - electromagnetic field coupling using the first analysis results as the load for the second analysis. In practice, ANSYS software can not convert and load this load automatically. Therefore, this thesis utilize Automatically Load and Load Conversion1.0 interface software developed by JAVA language in NetBeans platform to realize ANSYS multi-node load automatically load conversion successfully and complete the numerical simulation of multi-level reheating process.The law has been studied between the current density, frequency, preheat temperature and billet reheating process. With the current density, frequency, pre-heating temperature increasing, heating rate accelerates and heating time shortens. Although temperature of the surface and central node of semi-solid billet will expand, the uniformity of billet temperature changes little.By the simulation results, the better heating parameters of single-stage heating about 3.2e7A/m2, 2500Hz, 400℃can ensure heating rate and temperature uniformity of magnesium alloy semi-solid billet. However, the cycle time can not be met. The better heating parameters of multi-level heating are 3.2e7A/m2, 2500Hz, 400℃. These parameters not only can ensure the temperature uniformity of billets, but also meet cycle time (30-50s) and improve production efficiency.The multi-level electromagnetic induction heating device is designed with the reference of simulation results. Test results show that the device can meet cycle time, make billets temperature uniformity and non-liquid flow on the surface. The semi-solid casting requirements can be met.