激光熔覆纯镍熔池底部组织生长的相场法模拟  

Phase-Field Method Simulation of Microstructure Evolution at the Bottom of Melt Pool in Coaxial Laser Cladding

作　　者：孙道金[1] 刘继常[1] 李钦栋[1] 

机构地区：[1]湖南大学汽车车身先进设计制造国家重点实验室,湖南长沙410082

出　　处：《中国激光》2013年第4期93-98,共6页Chinese Journal of Lasers

基　　金：国家自然科学基金(51075134)资助课题

摘　　要：对纯镍同轴送粉激光熔覆过程中宏观温度场与熔池底部微观组织生长进行了二维耦合模拟计算。首先利用标志变量法计算因粉末的加入而产生的边界动态改变,进行宏观温度场模拟,再取熔池底部一宏观单元进行网格细化,作为微观模拟区域,并通过插值计算获得微观模拟区域的初始温度条件,同时在计算中用宏观单元温度实时修正微观计算区域温度边界条件。在微观区域底部设置晶核,确定相场初始条件,并采用相场法进行微观区域的相场、温度场耦合计算,获得微观组织形貌。最后进行试验,在镍板基底上熔覆镍粉,模拟所得微观组织形貌与试验所得基本吻合,验证了模拟结果的正确性。Two-dimensional macroscopic temperature field of the work-piece and evolution of the microstructure which is located at the bottom of the melt pool in coaxial laser cladding are calculated. Formation of the clad bead due to powder feeding is simulated. Macroscopic temperature field is computed. Then, one macroscopic cell at the bottom of the melt pool is re-meshed for calculation of the microstructure evolution. Initial temperature conditions are calculated with interpolation method among the temperatures of its nearest neighbor macroscopic cells. Its four boundary temperatures can be considered as the same as its four neighbors＇ temperatures. Crystal nucleus is set in the lower boundary of microscopic domain. Finally, phase field and temperature field are calculated using phase-field method. The calculation results agree with the experimental results, which proves the validity of the macro and micro coupling model.

关 键 词：激光技术 激光熔覆 相场法 宏微观耦合 数值模拟 

分 类 号：TN249[电子电信—物理电子学] TN241