钛合金电子束快速成形熔池传热及流动数值模拟.docVIP

  钛合金电子束快速成形熔池传热及流动数 值模拟# 汤群1，庞盛永1，陈彬斌1，锁红波1,2，周建新1* 5 10 15 20 25 30 35 40 （1. 华中科技大学 材料成形及模具技术国家重点实验室, 武汉 430074； 2. 北京航空制造工程研究所 高能束流加工技术国防科技重点实验室，北京 100000） 摘要：建立了 TC4 钛合金电子束快速成形过程熔池传热及流动的三维瞬态数值计算模型。 模型采用修正的热源模型来模拟高能电子束与沉积体之间的能量作用；综合考虑了热量传 递、熔池流动以及自由界面变形等耦合影响；同时全面考虑了反冲压力、热毛细力以及熔滴 的冲击力等因素对熔池流动的驱动作用；熔池自由界面采用 Level Set 方法进行追踪。研究 结果表明，熔池前部存在剧烈流动，同时热毛细力是熔池流动的主要驱动力；熔滴的冲击力 对熔池的传热以及流动具有周期性作用；高频率电子束椭圆扫描可使熔池的温度梯度以及流 动强度减小，但熔池流动规律不变。模拟得到的熔池形貌以及尺寸大小与实验结果对比验证， 模拟结果与实验结果吻合良好，证明了计算模型的准确性。 关键词：TC4 钛合金；电子束快速成形；传热；熔池流动；数值模拟 A three dimensional transient model for heat transfer and fluid flow of weld pool during electron beam freeform fabrication of Ti-6-Al-4-V alloy TANG Qun1, PANG Shengyong1, CHEN Binbin1, SUO Hongbo1,2, ZHOU Jianxin1 (1. State Key Laboratory of Materials Processing and Die Mould Technology, HuaZhong University of Science and Technolody, WuHan 430074; 2. National Key Laboratory of Power Beam Processing Technologies, Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100000) Abstract: A three-dimensional transient model is proposed to understand the heat transfer and fluid flow behaviors of weld pool during single track Electron Beam Freeform Fabrication (EBF3) of Ti-6-Al-4-V alloy. Fluid flows driven by recoil pressure, surface tension and thermal capillary effect are coupling considered in the model. Free surface evolutions of weld pool are incorporated with level set method. An improved heat source model is also proposed to simulate the energy interactions between high energy electrons and deposits. Results indicate that there are vigorous fluid flows in the front part of weld pool and thermal-capillary force is the main driven force of fluid flow. Effect of droplet impacting could periodically influence the heat transfer and fluid flow of weld pool. High frequency elliptical scanning of electron beam could decrease the temperature gradient and the magnitude of fluid flow of weld pool. However, beam scanning does not essentially cha