铁粉激光直接成形温度场数值模拟

Numerical Simulation of Temperature Field for Laser Direct Forming of Iron Powder

建立了激光直接成形三维温度场有限元模型,该模型考虑到了材料热物性参数随温度变化以及相变潜热。采用ANSYS有限元软件对铁粉的激光直接成形过程的三维瞬态温度场进行了数值模拟。模拟结果表明:热影响区的等温线形状呈现前密后疏;由于热积累效应,第二层的温度值要高于与第一层相同位置的温度值;随着激光功率增大,热流密度不断增加,熔池的温度越来越高,熔池尺寸也越来越大,导致液相存在时间过长从而加剧球化现象。

A three-dimensional finite element model was established for temperature field during laser direct forming （LDF）, with the variation of thermophysical properties of materials with temperature and the latent heat of phrase transformation taken into consideration. By using ANSYS software, numerical simulation of 3D transient state of temperature field during LDF was obtained. The simulation results show that the isotherm of heat affected zone （HAZ） presents to be denser in front end of molten pool than the back end. The temperature of the second layer is much higher than the first layer due to cumulative effect of heat. With an increase in laser power, which leads to a rise in the density of heat flow rate, the molten pool becomes increasingly higher in temperature and bigger in size. The result of longer-time in liquid phase aggravated bailing phenomenon.