马氏体时效钢激光选区熔化成形过程介观尺度数值模拟  

Mesoscopic Numerical Simulation during Selective Laser Melting of Maraging Steel

作　　者：宋军[1,2] 唐倩[1] 罗智超[1] 冯琪翔 聂云飞[1] 任治好 SONG Jun;TANG Qian;LUO Zhichao;FENG Qixiang;NIE Yunfei;REN Zhihao(College of Mechanical and Vehicle Engineering,Chongqing University,Chongqing 400044;State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology,Wuhan 430074;School of Advanced Manufacturing Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065)

机构地区：[1]重庆大学机械与运载工程学院,重庆400044 [2]华中科技大学材料成形与模具技术全国重点实验室,武汉430074 [3]重庆邮电大学先进制造工程学院,重庆400065

出　　处：《机械工程学报》2024年第3期282-295,共14页Journal of Mechanical Engineering

基　　金：国家自然科学基金(52335006,51975073)资助项目。

摘　　要：激光选区熔化(Selective laser melting,SLM)成形过程涉及多种发生于介观尺度下的物理现象,采用试验方法难以揭示物理现象复杂的形成规律。以18Ni-300马氏体时效钢为SLM成形材料,采用离散元法与有限体积法建立了SLM成形介观尺度热流耦合数值模型,并结合熔道成形试验验证模型的正确性。结合数值模拟揭示激光功率从60 W增加至270 W时单道SLM成形熔道形貌、熔池尺寸与温度、传热机制等熔池行为的基本特征;研究在0.2 J/mm、0.3 J/mm和0.45 J/mm线能量密度下不同激光功率和扫描速度组合对熔道形貌、熔池尺寸与传热机制的影响规律;结合熔道搭接理论模型计算激光功率180 W和扫描速度600 mm/s组合下无搭接缺陷的扫描间距理论临界条件约为83μm,并研究80μm、100μm和120μm扫描间距下多道多层SLM成形熔道搭接行为和演变规律。该模型可用于筛选工艺参数区间,提高工艺优化效率,为单层/多层成形的工艺试验提供指导。Selective laser melting(SLM) involves a variety of complex physical phenomena that occur at the mesoscale,and these complex physical mechanisms during processing are difficult to be uncovered using experimental methods.A mesoscopic heat-coupled numerical model for the SLM process of 18Ni-300 maraging steel is developed based on discrete element and finite volume methods,and the model is verified by comparison with track fabrication experiments.Numerical simulations are performed to reveal the basic characteristics of single-track SLM processing,including the morphology of the tracks,the dimensions and temperatures of the molten pool and the heat transfer mechanisms,when the laser power is increased from 60 W to 270 W.The influence of different combinations of laser power and scanning speed at the linear energy densities of 0.2 J/mm,0.3 J/mm and 0.45J/mm on the morphology of the tracks,molten pool dimension and the heat transfer mechanism is investigated.Furthermore,the theoretical critical hatch spacing without overlap defects for the laser power of 180 W and scanning speed of 600 mm/s is calculated to be 83 μm based on the theoretical relationship of track overlaps,and the behaviour and evolution of track overlaps during multi-track and multi-layer SLM processing are investigated at the hatch spacing of 80 μm,100 μm and 120 μm.The developed model can not only guide single-layer/multi-layer processing experiments,but also be used to predict process parameter windows and improve the efficiency of process optimisation..

关 键 词：激光选区熔化 马氏体时效钢 数值模拟 熔池 缺陷 

分 类 号：TG665[金属学及工艺—金属切削加工及机床]