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为了研究电磁搅拌对TA15钛合金激光熔池的影响,构建了一种三相三极旋转式电磁搅拌器作用下微小熔池内部的磁流体力学数学模型。运用该模型计算了不同激励电流情况下磁场中心处的磁感应强度和熔池内熔体周向流速,分析了其对熔池温度分布和组织形成的影响。并采用试验手段对分析计算结果进行了验证。结果表明:电磁力驱使熔体作周向运动,且随着远离磁场中心,洛伦兹力越大,周向流速越大。随着激励电流的增大,磁感应强度增强,熔质周向流速增大。流速加剧能够降低熔池内温度及凝固界面处的温度梯度,有利于等轴晶的增多。试验证明施加磁场后熔池顶部组织出现等轴晶,且随着远离磁场中心,熔池顶部的等轴晶数量逐渐增多,与计算结果的分析趋势相吻合。
In order to study the influence of electromagnetic stirring on TA15 titanium laser pool, a mathematical model of MHD inside the micro-pool under the action of three-phase three-pole rotating electromagnetic stirrer was established. The model was used to calculate the magnetic flux density at the magnetic field center and the circumferential velocity of melt in the molten pool under different excitation currents. The effect of temperature on the distribution and microstructure of the molten pool was analyzed. The results of the analysis and calculation are verified by means of experiments. The results show that the electromagnetic force drives the melt to make a circumferential movement, and as the distance from the magnetic field center increases, the Lorentz force increases and the circumferential velocity increases. As the excitation current increases, the magnetic flux density increases, and the melt velocity increases in the circumferential direction. Increased flow rate can reduce the temperature in the weld pool and the temperature gradient at the solidification interface, which is beneficial to the increase of equiaxed grains. The experiment proves that equiaxed grains appear at the top of the weld pool after the magnetic field is applied, and the number of equiaxed grains at the top of the weld pool increases with the distance from the center of the magnetic field, which agrees with the analysis trend of the calculated results.