扫描策略对激光粉末床熔融W-Ti重合金致密化、残余应力及力学性能的影响  

Effects of Laser Scan Strategies on Densification,Residual Stress,and Mechanical Properties of W-Ti Heavy Alloy Fabricated by Laser Powder Bed Fusion

作　　者：郭朦 刘凯[1,2] 孙婧佳 顾冬冬 Guo Meng;Liu Kai;Sun Jingjia;Gu Dongdong(College of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,Jiangsu,China;Jiangsu Provincial Engineering Laboratory for Laser Additive Manufacturing of HighPerformance Metallic Components,Nanjing 210016,Jiangsu,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210016 [2]江苏省高性能金属构件激光增材制造工程实验室,江苏南京210016

出　　处：《中国激光》2023年第4期23-33,共11页Chinese Journal of Lasers

基　　金：科学挑战专题项目(TZ2018006-0301-02,TZ2018006-0303-03);基础加强计划技术领域基金项目(2019-JCJQ-JJ-331);江苏省第十五批“六大人才高峰”创新人才团队项目(TD-GDZB-001);国家自然科学基金创新研究群体项目(51921003);江苏省研究生科研创新计划项目(KYCX20_0193)。

摘　　要：采用激光粉末床熔融(LPBF)增材制造技术在不同扫描策略(岛状、之字形、重熔扫描策略)下制备了W-Ti重合金,研究了扫描策略对W-Ti合金致密化行为、残余应力分布及纳米硬度、抗压强度、断裂应变等力学性能的影响规律。研究结果表明:使用岛状扫描策略可以有效抑制试样内部的孔隙、裂纹等冶金缺陷,且成形件层间冶金结合良好,致密度可达99.4%;岛状扫描策略下成形试样的残余应力分布较均匀,纳米硬度为8.44 GPa,极限抗压强度和断裂应变可达1906 MPa和20.4%,均为三种扫描策略下的最高值。本实验研究明晰了激光扫描策略与LPBF成形W-Ti合金力学性能之间的关系,优化了难加工W-Ti重合金的激光增材制造工艺。Objective Owing to the high melting point,high thermal conductivity,high creep resistance,high physical sputtering rate,and low hydrogen retention of tungsten(W)and its alloys,W has been widely used in the nuclear industry as well as rocket nozzles,medical protection,and other industrial fields.However,W is difficult to process,with a high ductilebrittle transition temperature(DBTT,200-400℃).Traditional processing methods,such as powder metallurgy,plasma sintering,and hot isostatic pressing,are unable to realize the formation of complex components from W,limiting its engineering application.Fortunately,the development of laser powder bed fusion(LPBF)additive manufacturing provides a feasible method for fabricating W.In this study,we design a W-Ti heavy alloy and successfully fabricate it using LPBF.We investigate the effects of laser scan strategies on the densification,residual stress,and mechanical properties of LPBFprinted W-Ti heavy alloys,and further optimize the laser scan strategy.We hope that these findings can promote the optimization of laser additive manufacturing of difficult-to-process W-Ti heavy alloys by elaborating the relationship between the laser scan strategy and the properties of the LPBF-fabricated W-Ti alloy.Methods Pure W and Ti spherical powders were used in this study.First,W and Ti powders were mixed uniformly by mechanical milling under an argon atmosphere.Then,the mixed powder was processed using self-developed LPBF equipment according to a CAD model.After printing,the samples were cut from the substrate and subjected to ultrasonic cleaning.The relative density of W-Ti was measured using the Archimedes method.The microstructure and densification behavior were characterized using an optical metallographic microscope(PMG3).The phase composition and residual stress were analyzed using an X-ray diffractometer(Bruker D8 Advance).An FEI Quanta 200 scan electron microscope equipped with an energy-scattering spectrometer was used to observe the surface morphology.To characterize the mechani

关 键 词：激光技术 激光粉末床熔融 扫描策略 W-Ti重合金 残余应力 力学性能 

分 类 号：TG146.411[一般工业技术—材料科学与工程]