激光粉末床熔融成形内部质量缺陷及其调控方法  

Internal Defects and Control Methods of Laser Powder Bed Fusion Forming

作　　者：宋长辉[1] 付厚雄 严仲伟 曾永杰[2] 周瀚翔 杨永强[1] Song Changhui;Fu Houxiong;Yan Zhongwei;Zeng Yongjie;Zhou Hanxiang;Yang Yongqiang(School of Mechanical&Automotive Engineering,South China University of Technology,Guangzhou 510641,Guangdong,China;The Library of South China University of Technology,Guangzhou 510641,Guangdong,China)

机构地区：[1]华南理工大学机械与汽车工程学院,广东广州510641 [2]华南理工大学图书馆,广东广州510641

出　　处：《中国激光》2022年第14期261-277,共17页Chinese Journal of Lasers

基　　金：国家自然科学基金(U2001218);广东省基础与应用基础研究基金(2020B1515120013);广东省重点领域研发计划(2020B090923001);首都卫生发展科研专项(2020-2-5131);北京市自然科学基金(L192066);广东省特支计划(2019TQ05Z110)。

摘　　要：激光粉末床熔融(Laser Powder Bed Fusion,LPBF)成形工艺的特殊性决定其在生产过程中存在巨大的温度梯度、剧烈的物相变化以及极不稳定的熔池,易使零件产生内部质量缺陷,而这些缺陷会直接影响零件的成形质量和力学性能。从致密度和残余应力两个角度出发,对LPBF成形零件的内部质量缺陷进行分类并对其典型特征、形成机理及其造成的影响进行论述。此外,分别讨论了成形工艺调控方式和新型复合制造调控方式对缺陷的调控作用,其中激光波长和光斑形貌的调整、增减材复合和多能量场复合的调控方式在未来有望成为LPBF成形工艺内部缺陷调控的重要研究方向。Significance Additive manufacturing(AM)has been widely used in aerospace,military,medical,automotive,nuclear power,and other fields due to its great potential in producing lightweight parts with complex structures and high personalization.As one of the most widely used AM technologies,laser powder bed fusion(LPBF),also known as selective laser melting,is characterized by huge temperature gradients,drastic phase changes,and extremely unstable molten pools.Because of its particularity in the manufacturing process,there easily exist internal defects of parts and harmful influence on forming quality and mechanical properties.Some of the defects cause the reduction of density,and further reduce other mechanical properties.For example,micropores and lack of fusion lead to the reduction of density,resulting in the decrease of its strength,hardness,and fatigue strength.The balling and spattering caused by lack of fusion also influence the surface morphology and phase composition.In addition,the residual stress generated in the machining process also causes cracks and warping deformation.The cracks influence the performance,while warping deformation influence the dimensional accuracy.Therefore,it is of great significance to understand the characteristics,formation mechanism,and influencing factors of defects,so as to explore the control mechanism of defects and control the quality and performance of parts.Process This paper introduces the characteristics,formation mechanism,and influence of common defects on density,including unmelting caused by lack of fusion(Fig.2),balling(Fig.3),spatter(Fig.5)and micropores(Fig.6),and the crack(Fig.7)and warping deformation(Fig.8)caused by residual stress.The effects of control methods of forming process and composite manufacturing on defects are discussed.The control methods of forming process can be classified into five categories;process gas supply,powder bed,laser beam,processing parameters,and scanning strategy(Fig.9).A suitable processing environment and powder bed are the basis

关 键 词：激光技术 激光粉末床熔融成形 内部缺陷 工艺优化 复合调控 

分 类 号：V261.8[航空宇航科学与技术—航空宇航制造工程] TN249[电子电信—物理电子学]