高强铝合金7075激光粉末床熔融凝固裂纹的消除与质量控制  

Solidification Crack Elimination and Quality Control of High-Strength Aluminum Alloy 7075 Fabricated Using Laser Powder Bed Fusion

作　　者：吕新蕊 刘婷婷[1,2] 廖文和[1,2] 韦辉亮 杨涛 蒋立异[1,2] Lu Xinrui;Liu Tingting;Liao Wenhe;Wei Huiliang;Yang Tao;Jiang Liyi(School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China;National Joint Engineering Laboratory for Numerical Control Forming Technology and Equipment,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]南京理工大学机械工程学院,江苏南京210094 [2]南京理工大学数控成形技术与装备国家地方联合实验室,江苏南京210094

出　　处：《中国激光》2022年第14期177-187,共11页Chinese Journal of Lasers

基　　金：国家重点研发计划(2017YFB1103000);国家自然科学基金(51805267)。

摘　　要：激光粉末床熔融(LPBF)技术是近年来快速发展的一种增材制造技术,高强铝合金具有低密度、高强度的特点,如何使用LPBF技术高质量地打印高强铝合金成为近年来的研究热点。本课题组创新性地将含Zr的非晶合金引入到7075高强铝合金中,探究了含Zr非晶合金对7075高强铝合金LPBF打印质量的影响。研究发现,含Zr非晶合金的添加可以有效实现晶粒细化,对于7075高强铝合金LPBF打印过程中的凝固裂纹具有明显的抑制作用。通过改变工艺参数探究了激光功率、扫描速度和扫描间距对单层单道、单层多道以及实体打印件的影响规律。通过正交试验发现致密度和显微硬度最优的工艺参数区间为激光功率300~340 W,扫描速度600~800 mm/s,扫描间距50~70μm,并在激光能量密度为142.9 J/mm^(3)时得到了致密度为99.4%、显微硬度为154.4 HV的块体试样。本研究对于提高高强铝合金LPBF可打印性以获得质量稳定的无缺陷打印件具有重要意义。Objective Laser powder bed fusion(LPBF)technology is a new type of manufacturing method.The three-dimensional(3D)model is sliced using a software,and then,powder is scanned and melted layer-by-layer using laser to obtain a 3D entity.The most studied LPBF alloys mainly include titanium alloys,cobalt-chromium alloys,and nickel-based superalloys.Meanwhile,the most studied LPBF formed aluminum alloys are Al-Si alloys,such as Al S10Mi g.Highstrength aluminum alloys represented by 7075 have high hardness and strength and have unique advantages in aerospace and weapon manufacturing industries.However,the wide solidification interval of high-strength aluminum alloys and poor welding performance,defects,such as solidification cracks during the LPBF process,significantly affect the mechanical properties of the LPBF high-strength aluminum alloys,and thus restrict their application in the additive manufacturing field.Current research on the LPBF forming of high-strength aluminum alloys,such as 7075,mainly focuses on material modification and process optimization.This study explores the effect of a Zr-containing amorphous alloy on the forming quality of 7075 high-strength LPBF aluminum alloy.A printed workpiece with stable quality without cracks and defects was obtained.Our study can improve the LPBF printability of high-strength aluminum alloys and promote the expansion of the available engineering material library and process parameter library for additive manufacturing.Methods The Zr-containing amorphous and 7075 high-strength aluminum alloys powders were uniformly mixed in a mass ratio of 2;23 through mechanical powder mixing to obtain composite powder.First,a single-track printing experiment was performed to explore the effects of laser power and scanning speed on the morphology of the single-track channel and the size of the molten pool.Then,a single-layer printing experiment was performed to measure the surface roughness of the printed single-layer and study the effects of the hatch distance on surface quality.Finally,

关 键 词：激光技术 激光粉末床熔融 高强铝合金 凝固裂纹 微观组织 

分 类 号：TG146.21[一般工业技术—材料科学与工程]