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T15高速钢异质材料激光熔覆过程的多相流模型
王翔宇1,2, 王罡1,2, 罗升3, 尤浩兴3, 融亦鸣3
1.清华大学 摩擦学国家重点实验室, 北京 100084;2.清华大学 精密超精密制造装备及控制北京市重点实验室, 北京 100084;3.南方科技大学 机械与能源工程系, 深圳 518055
摘要:
激光熔覆过程中熔池的演变包含能量输入、质量添加、高温金属液体流动、金属熔化凝固以及材料扩散等复杂过程。基于多相流理论,建立了T15高速钢在42CrMo基板上激光熔覆的物质传输模型。其中,质量添加与能量输入过程采用添加在熔池表面单元的源项模拟,而气液界面的捕捉则采用了CLSVOF方法。通过试验获得的熔覆层关键形貌参数,被用来验证数值模型的有效性。结果表明,T15高速钢由于其自身含有较高的硫含量,在激光熔覆熔池中,在Marangoni力的驱动下具有明显内向流动的特征。高温液体向下流动,形成较大的熔深。以熔覆层高度、深度、稀释率等3个形貌参数为比较依据,验证了异质材料激光熔覆的多相流模型,在不同工艺参数组合下试验值与仿真值均具有较好的一致性,证明了该模型可准确反映激光熔覆过程熔池内的微流动与物质传输行为。
关键词:  激光熔覆  多相流  马朗戈尼效应  表面活性元素
DOI:10.11933/j.issn.1007-9289.20181026001
分类号:TG174.44
基金项目:国家自然科学基金(U1537202,51535011);十三五预研课题(41423060102)
Multi-phase Flow Modelling of Laser Cladding Process with T15 High Speed Steel Particles
WANG Xiangyu1,2, WANG Gang1,2, LUO Sheng3, YOU Haoxin3, RONG Yiming3
1.State Key Laboratory of Tribology & Institute of Manufacturing Engineering, Tsinghua University, Beijing 100084, China;2.Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Tsinghua University, Beijing 100084, China;3.Mechanical and Energy Engineering Department, Southern University of Science and Technology, Shenzhen 518055, China
Abstract:
During the laser cladding process, the transport phenomenon in the molten pool are complex including intense energy input, mass addition, strong fluid flow, rapid solidification, melting and species transport. In order to simulate the process of depositing T15 powders on 42CrMo base steel through laser cladding, a multiphase species transport model was developed in which CLSVOF method was adopted to capture the gas-liquid interface and source terms were precisely added under the interface serving as the energy input and mass addition. The model was validated by several characteristic parameters of cladding layers obtained by single track cladding experiments. As the sulphur content of T15 was relatively high, which changed the direction of Marangoni force, the molten pool showed an obvious inward flow pattern. Results show that high temperature fluids are driven downward and consequently a deep fusion penetration is achieved. The consistence of charactistic parameters including cladding height, depth and dilution between experiment and simulation results under different process parameters indicate that the model is operative in investigating the laser cladding process.
Key words:  laser cladding  multiphase flow  marangoni effect  surface active element