基于热-流耦合模型研究激光熔覆速度场影响机制  被引量:4

Study on the Effect Mechanism of Laser Cladding Velocity Field Based on Thermal-Fluid Coupling Model

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作  者:赵明娟[1,2] 李宝星 吴涛[1] 赵龙志[1,2] 曾建邦[1] 焦海涛 李劲 宋立军 Zhao Mingjuan;Li Baoxing;Wu Tao;Zhao Longzhi;Zeng Jianbang;Jiao Haitao;Li Jin;Song Lijun(Key Laboratory of Advanced Materials for Vehicles&Laser Additive Manufacturing of Nanchang City,East China Jiaotong University,Nanchang 330013,China;State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure,East China Jiaotong University,East China Jiaotong University,Nanchang 330013,China;Tongda industry and Trade Co.,Ltd.,Nanchang Railway Administration,Nanchang 330002,China;College of Mechanical and vehicle engineering,Hunan University,Changsha 410082,China)

机构地区:[1]华东交通大学载运工具先进材料与激光增材制造南昌市重点实验室,江西南昌330013 [2]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013 [3]南昌铁路局通达工贸有限责任公司,江西南昌330002 [4]湖南大学机械与运载工程学院,湖南长沙410082

出  处:《华东交通大学学报》2022年第4期74-83,共10页Journal of East China Jiaotong University

基  金:国家自然科学基金项目(51965022);江西省自然科学基金项目(20202BABL204046);江西省教育厅科技项目(200606)。

摘  要:激光熔池内部熔体的对流状况会直接影响到熔覆层内气孔、裂纹和内部热应力等缺陷的形成,这些缺陷会显著影响熔覆层的服役行为,分析熔池内部的对流状况对控制熔覆层质量具有重要意义。通过构建激光熔覆过程的热-流耦合模型,并利用其模拟不同激光功率和送粉率下的熔覆过程,研究熔池深度和宽度,模型模拟了激光熔覆过程中工艺参数对熔池温度场及速度场的影响。结果表明:工艺参数中的激光功率、光斑半径和扫描速度的改变,均会明显影响熔池内熔体流速峰值和峰值上升速度,而送粉率对熔池速度场几乎无影响。此外,表面张力系数对熔池内熔体速度场也有影响,熔覆材料的表面张力系数为负值时,熔池内熔体从激光照射区域向两边流动,使得熔池变浅变深;而含S等活性元素的熔覆材料具有正表面张力系数,熔池内流体从熔池两边向中间流动,使熔池变深变窄;随着表面系数绝对值的增大,熔池内流体速度峰值也会随之增大。The velocity distribution in the molten pool has a significant impact on the cladding depth and width of the laser cladding layer and the surface morphology, which in turn affects the quality of the cladding layer. To this end, a thermal-fluid coupling model of laser cladding is constructed, and the cladding process under different laser power and powder feed rate is simulated by using it. Therefore, this paper uses this model to deeply study the effect of laser process parameters on the temperature field and the velocity field in the molten pool. It was found that as the laser power increases, the spot size or the scanning speed decreases, the peak value of the fluid flow velocity in the molten pool increases during the rising period, and the decline in the peak period of the flow velocity decreases gradually or even stabilizes. while the change of the powder feed rate has almost no effect on the velocity field. In addition, the influence of the surface tension coefficient on the velocity field in the molten pool is also studied.For the cladding material with negative surface tension coefficient, It was found that the fluid in the molten pool flows from the laser irradiation area to both sides, which makes the molten pool shallower and deeper.The cladding material containing active elements such as S has a positive surface tension coefficient, and the fluid in the molten pool flows from both sides of the molten pool to the middle, which makes the molten pool deeper and narrower. As the absolute value of the surface coefficient increases, the fluid velocity peaks will increase with it.

关 键 词:热-流耦合模型 速度场 工艺参数 表面张力系数 

分 类 号:TG174.44[金属学及工艺—金属表面处理] U216[金属学及工艺—金属学]

 

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