基于VOSET方法的高温金属熔池演化研究

Evolution of High Temperature Metal Molten Pool Based on VOSET Method

增材制造过程熔池的演化研究是当前热点之一,但数值研究过程中通常存在由于模型简化过多或模型界面追踪不精确所导致的结果预测精度较低的问题。为了改善上述问题,本研究引入VOSET界面追踪方法并基于其建立了完整的金属熔池数值模型,同时通过激光热源加热铜板的实验验证模型正确性,最后在此基础上揭示了金属熔池的基本演化过程并分析其形成的原因。主要结论如下:激光沉积金属表面后,急剧上升温度梯度诱发切向马尔戈尼对流,对流作用快速增强并主导熔池演化,自由液面变形和熔池尺寸快速增大;受到水平物质输运的作用,熔池的切向演化相较于法向更加剧烈;熔池演化一段时间后会进入准稳态过程,此时其演化过程逐渐趋于平缓。

The study of the evolution phenomena of the melt pool during additive manufacturing(AM) process is a hot topic in current.However,due to too much model simplification and an imprecise interface capture in the numerical study of the melt pool,the forecast precision is relatively low.In order to improve the accuracy of predication,a VOSET interface capture method is introduced and based on which a numerical metal melt pool model is established.Meanwhile,the corresponding experimental studies are carried out for validation.At last,the basic evolution phenomena and its formation mechanisms of the melt pool are clearly revealed.The main results are drawn.During the laser deposition on metal surface,tangential Marangoni convection is induced by a sharp rise in temperature gradient,the convection effect increases rapidly and gradually dominates the evolution of melt pool.Both of the deformation of the free surface and the size of melt pool increase rapidly,and the tangential evolution is more vigorous.After a while,the heat deposition and dissipation in melt pool are dynamically balanced,and the melt pool evolution enters a quasi-steady state.