摘要
目的 针对多光束激光选区熔化加工拼接重叠区域的质量控制难题,研究拼接重叠区域的缺陷形成机理与控制手段。方法 通过建立激光选区熔化介观尺度高保真数值模型,基于流体体积法和射线追踪热源,还原粉末熔化凝固的加工过程,研究不同加工参数下拼接重叠区域熔池动力学和激光反射吸收行为,并对比分析拼接重叠区域和非拼接重叠区域激光-材料能量耦合机制。结果 在拼接重叠区域大小不同的情况下,重叠区域长度分别为160、200、240μm时,其拼接重叠区域熔道宽度宽于非拼接重叠区域,拼接重叠区域与非拼接重叠区域存在高度差,且重叠区域的全局激光吸收率要高于非重叠区域,其中重叠区域皆有孔隙缺陷,重叠区域240μm长度方案下的全局平均吸收率达到最高(0.417 56)。在拼接重叠区域长度为240μm、扫描速度为0.9 m/s和1.2 m/s时,由于获得的能量低于扫描速度为0.6 m/s时的能量,其重叠区域不存在孔隙缺陷。结论 拼接重叠区域的表面形貌和孔隙缺陷与熔池动力学和激光反射吸收行为密切相关,合适的加工参数可以改善拼接重叠区域的成形质量。
The quality control problem of the stitching overlap area of multi-beam selective laser melting processing was studied to investigate the defect formation mechanism and control means of the stitching overlap area. Due to the difficult observation of the interaction behavior between laser and material during selective laser melting, based on the volume of fluid method and ray-traced heat source, the process of powder melting and solidification was restored by establishing a high-fidelity numerical model of selective laser melting at mesoscopic scale to study the melt pool dynamics and laser reflection & absorption behaviors in the spliced overlap region under different processing parameters, and to compare and analyze the laser-material energy coupling mechanism in the spliced overlap region and the non-spliced overlap region, to explore means of suppressing defects in overlapping regions of splicing. The numerical simulation model was based on computational fluid dynamics theory and a multiphase flow model with the finite volume method was used and combined with physical field models such as melting and solidification, heat loss, surface tension, recoil pressure, and ray tracing heat source. A single-pass numerical simulation of laser-selected melting was performed at a laser power of 430 W, in which there was no interruption time between the two laser beams, and the second beam was processed immediately after the completion of the first beam, and the two beam scans were of equal length. The two beams were in one scanning path, and the starting point of the second beam scan was before the end point of the first scan, resulting in a stitching overlap region. Numerical simulations were performed at the same stitching overlap area scan speed, different stitching overlap area size and the same stitching overlap area size, different stitching overlap area scan speed, where the non-stitching overlap area scan speed in both cases was 0.6 m/s. With different sizes of spliced overlap regions, the spliced overlap regions h
作者
李泓历
傅广
任治好
李舒玥
彭庆国
肖华强
李少波
LI Hong-li;FU Guang;REN Zhi-hao;LI Shu-yue;PENG Qing-guo;XIAO Hua-qiang;LI Shao-bo(School of Mechanical Engineering,Guizhou University Guiyang 550025,China;State Key Laboratory of Public Big Data,Guizhou University Guiyang 550025,China;College of Mechanical and Vehicle Engineering,Chongqing University,Chongqing 400044,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第11期406-418,共13页
Surface Technology
基金
贵州省科学技术基金项目[黔科合基础-ZK(2021)一般268]
国家自然科学基金(52065009)
国家重点研发计划(2020YFB1713300)
贵州大学引进人才科研项目(贵大人基合字[2021]87) 。
关键词
激光选区熔化
数值模拟
重叠区域
激光吸收
熔池演变
selective laser melting
numerical simulation
overlap region
laser absorption
molten pool evolution
