Numerical simulation of an electromagnetic weld pool control for high power laser beam welding of high thickness metal parts

本项目一期高功率激光束焊接almg3合金厚板和304型奥氏体不锈钢的电磁熔池控制计算机模拟及实验验证的积极结果表明，该技术具有良好的应用前景。该技术在铁磁性材料方面的扩展似乎非常有吸引力。在最初的项目中已经考虑了延长选项。热影响区内的熔融金属和部分材料在居里温度（TCurie）以上过热时，不表现出铁磁性。工件的其余部分是铁磁性的，阻碍了产生的磁场向熔池的转移。为了最大限度地减少铁磁区的影响，我们建议将强直流磁场引导到材料中，以使工件磁化超过饱和极限。实验试验将首先在轻铁磁双相钢上进行，在低磁场强度值下应用这种方法是可能的。对于这种材料，1t的磁场值足以使磁畴的方向与外磁场的方向相对应。因此，有效渗透率很低。铁磁区模拟将使用OPERA软件进行，该软件可以模拟铁磁材料中的温度相关磁滞和饱和效应等非线性效应。在熔池区，采用COMSOL-Multiphysics进行新的计算机模拟。这将使用opera - simulation的结果作为铁磁和非铁磁区域边界的边界条件（T = TCurie）。焊接试验和计算机模拟的结果将转移到普通低碳钢上。

The positive results of computer simulation of electromagnetic meltpool control as well as their experimental verification for high power laser beam welding of thick plates of AlMg3-alloy and austenitic stainless steel Type 304 gained in the first phase of the project show good perspectives for applicability of this technology. The extension of the technology for the case of ferromagnetic materials seems to be very attractive. The prolongation option was already considers in the original project. The molten metal and partially the material in HAZ, which is overheated above the Curie-Temperature TCurie , do not exhibit ferromagnetic properties. The rest part of the workpiece is ferromagnetic and hinders the transfer of generated magnetic fields to the meltpool. In order to minimize the influence of the ferromagnetic zone we suggest to guide a strong DC magnetic field into material, in order to magnetize the workpiece over the saturation limit. The experimental trials will take place first with light ferromagnetic duplex steel, where application of this method would be possible at low magnetic field strength values. For this material the magnetic fields values of 1 T would be enough for orientation of magnetic domains correspondent to direction of the external magnetic field. Herewith the effective permeability is very low. The simulation of ferromagnetic zone will take place by using of OPERA software, which enables a simulation of nonlinear effects like temperature dependent hysteresis and saturation effects in ferromagnetic materials. In molten pool zone the new computer simulation by means of COMSOL-Multiphysics will be carried out. This will use the results of OPERA-Simulations as boundary conditions at the border between ferromagnetic and non-ferromagnetic regions (T = TCurie) .The results obtained from welding trials and computer simulations will be transferred to the normal mild steels.