摘要
目的针对选区激光熔化成形带较薄水平悬垂结构零件时表面形貌较差的问题,研究支撑间隔、支撑形式以及能量输入的大小对支撑上方悬垂结构初始层形貌的影响。方法利用选区熔化技术制备带支撑的316L水平悬垂结构初始层成形试样,通过截面金相分析和表面形貌数据分析,探究初始层熔融金属在冷却凝固前形貌的影响因素,以及变化过程机制。结果随着支撑间隔从2.5 mm减小至0.714 mm,激光能量输入由0.083 W·s/mm增加至0.25 W·s/mm,悬垂结构初始层的孔隙逐渐减少,最低孔隙率为6.549%。表面凸起球化最大高度由523.454μm降低至最小267.951μm,成形表面更为平整。相同排布方式下,线形连续支撑成形试样的孔隙更少。结论支撑间隔影响相邻支撑间受激光扫描熔融形成的熔融金属量,激光能量输入的大小将影响相同散热速率下熔融金属所需的凝固时间。受到扰动而破裂的熔融金属薄膜在表面张力作用下,将不断向与支撑结构连接处汇聚球化,初始层形貌不断偏离初始的平整薄层状态。使用十字交叉排布方式支撑间隔在1 mm以下的线形连续支撑,可以有效减少SLM成形水平悬垂结构初始层的孔隙数量,并提高初始层形貌的平整程度。
In view of the problems such as poor forming quality of thin horizontal overhanging structure morphology and the connection quality between support structure and overhanging structure formed by selective laser melting.The horizontal overhanging structure initial layer morphology of molten metal formed by selective laser melting was studied from three factors of support spacing,support form and energy input to provide a theoretical basis for improving the quality of thin horizontal overhanging structure and the connection quality between support structure and overhanging structure.316L parts of horizontal overhanging structure initial layer was prepared by selective laser melting technology.The influencing factors and changing process mechanism of the molten metal morphology in the initial layer before cooling and solidification were investigated by section metallographic analysis and surface topography data analysis.The spacing distances of support for the formed parts were set at 2.5,1.67,1.25,1,0.833 and 0.714 mm respectively,depending on the different amount of support structures for the uniformly divided 10 mm diameter circular model.The spacing distances of support were divided into the circular arrangement,which had fewer effects on the surface morphology,and the cross arrangement,which was more common in practice.The energy input of the initial layer increased with the decrease of the scanning speed and the increase of the laser power at constant laser power.With the decrease of the support spacing distance from 2.5 mm to 0.714 mm,the radio of pore in overhanging structure initial layer decreased continuously and the minimum pore radio can reach 6.549%.When the support spacing distance was 1 mm and with the increase of laser energy input from 0.083 W·s/mm to 0.25 W·s/mm,the pore radio can reach 13.104%.The maximun spheroidizing height of initial layer decreased from 523.454μm to 267.951μm,and the forming surface was more smooth.For the same spacing distances of support and support arrangement modes,the
作者
李梓杉
杨高林
董刚
姚建华
LI Zi-shan;YANG Gao-lin;DONG Gang;YAO Jian-hua(Institute of Laser Advanced Manufacturing,Zhejiang University of Technology,Hangzhou,310023,China;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou,310023,China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment,Zhejiang University of Technology,Hangzhou,310023,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第3期379-387,437,共10页
Surface Technology
基金
国家自然科学基金(52035014)
浙江省基础公益研究计划(LGG22E050036,LGG20E050019)。
关键词
选区激光熔化
支撑
水平悬垂结构初始层
连接质量
形貌
孔隙率
selective laser melting
support
horizontal overhanging structure initial layer
connection quality
morphology
radio of pore
