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首页> 外文期刊>International Journal of Heat and Mass Transfer >Numerical investigation of interfacial dynamics for the melt pool of Ti-6A1-4V powders under a selective laser
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Numerical investigation of interfacial dynamics for the melt pool of Ti-6A1-4V powders under a selective laser

机译：选择性激光作用下Ti-6A1-4V粉末熔池界面动力学的数值研究

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摘要

The complex evolution of a melt pool of Ti-6Al-4V powder particles under a moving selective laser was studied numerically. A laser power of 175 W and scanning speeds of 850, 1250, and 1650 mm/s were used. An effective laser source term with a time-varying maximum intensity was applied to a representative cross section to simplify the three-dimensional problem into a two-dimensional computational domain. The numerical results were validated using experimental observations. The effects of surface tension, Marangoni, and recoil forces on the interfacial morphology were investigated numerically.For a scanning speed of 1250 mm/s, the Marangoni effect initially begins to pull the interfacial melting flow from the laser focus region to the lateral powder. Meanwhile, the accumulated laser energy leads to evaporation, producing a corresponding recoil force. The transport phenomena caused by the Marangoni effect and the inward recoil force contribute to the local suppression of the melt pool. The Marangoni flow conveys the laser energy to the lateral powder, which significantly enhances the wetting phenomenon. In the next stage, the surface tension force gradually becomes dominant, eliminating the local suppression and concave curvature. The interfacial curvatures in this stage overshoot when they change signs. This tendency results in a periodic sloshing motion and oscillation of the melt pool.This study provides a thorough understanding of the wetting and morphology of the melt pool from a microscopic viewpoint, which could result in detailed design guidelines. (C) 2019 Elsevier Ltd. All rights reserved.
机译：数值研究了移动选择性激光作用下Ti-6Al-4V粉末颗粒熔池的复杂演化。使用175 W的激光功率和850、1250和1650 mm / s的扫描速度。将具有随时间变化的最大强度的有效激光源项应用于代表性横截面，以将三维问题简化为二维计算域。数值结果通过实验观察得到了验证。数值研究了表面张力，Marangoni和反冲力对界面形态的影响。在1250 mm / s的扫描速度下，Marangoni效应最初开始将界面熔化流从激光聚焦区域拉向横向粉末。同时，积累的激光能量导致蒸发，产生相应的反冲力。由马兰戈尼效应和向内反冲力引起的传输现象有助于局部抑制熔池。 Marangoni流将激光能量传递到侧面粉末，这大大增强了润湿现象。在下一阶段，表面张力逐渐占主导地位，消除了局部抑制和凹曲率。当它们改变符号时，该阶段的界面曲率会过冲。这种趋势会导致熔池周期性的晃动和振荡。本研究从微观角度全面了解了熔池的润湿性和形态，从而可以制定详细的设计指南。 （C）2019 Elsevier Ltd.保留所有权利。

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