送粉多道搭接激光熔覆温度场的数值模拟  

Numerical simulation of temperature field in multi-track overlapping powder-feeding laser cladding

作　　者：张俊[1] 宋建丽[1] 李永堂[1] 

机构地区：[1]太原科技大学材料科学与工程学院,山西太原030024

出　　处：《金属热处理》2012年第10期87-91,共5页Heat Treatment of Metals

基　　金：国家自然科学基金(50675136);山西省留学回国人员基金(200972);山西省青年学术带头人启动基金(2007)

摘　　要：运用ANSYS有限元分析软件,对送粉式多道搭接激光熔覆过程的温度场进行了数值模拟。考虑到材料热物性的非线性特征以及对流换热的边界条件,建立了三维有限元模型;送粉过程及熔覆单元的生长过程采用"生死单元法"来实现。结果表明:在多道搭接激光熔覆过程中,先凝固的熔覆道对后续搭接熔覆道有预热作用,两者之间存在一个初始温度差;在熔覆层中,搭接区的温度高于其它区域,存在重熔现象;熔覆层每道熔池节点的热循环曲线呈现周期性变化且基本相似;熔覆层易出现端部效应问题;熔覆层中上部温度梯度沿激光扫面方向水平分布,下部与扫描方向垂直分布,在基体与熔覆层交界处温度梯度出现突变和最大值,是裂纹高发区。The numerically simulation of temperature field was carried out by the ANSYS software in multi-track overlapping powder-feeding laser cladding. 3-D finite element model was found, which nonlinear characteristics of the material thermal properties and the boundary conditions of the convective transfer heat were considered. In the process of numerical simulation, the process of powder failing into the substrate and cladding element growing was accomplished by ＂element birth and death technology＂. The results show that the primarily solidification of cladding track to the following overlapping cladding track has a preheating function in the process of multi-track overlapping laser cladding. The temperature of the overlapping areas is higher than other areas in the cladding layer, and the overlapping areas exist remelting phenomenon. The thermal cycling curves of the molten pool nodes takes on periodic variation and basic similar in every track cladding. The end effect problem is apt to happen in cladding layer. The temperature gradient level distribution along the laser scanning direction in the top and perpendicular distribution in the bottom, the temperature gradient appearances mutation and maximum value in the junction of the substrate and cladding layer, where the crack can be caused easily.

关 键 词：激光熔覆 数值模拟 温度场 生死单元 温度梯度 

分 类 号：TG174.44[金属学及工艺—金属表面处理]