热处理对激光选区熔化IN718合金室温低周疲劳性能的影响  

Effect of Heat Treatment on Low⁃Cycle Fatigue Properties of Selective Laser Melted IN718 at Room Temperature

作　　者：冯星涛 李健民 耿硕 池煜璟 仪登豪 张冬云[1,2,3] Feng Xingtao;Li Jianmin;Geng Shuo;Chi Yujing;Yi Denghao;Zhang Dongyun(Institute for Laser Engineering,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;Beijing Engineering Research Center of 3D Printing for Digital Medical Health,Beijing 100124,China;Beijing International Science and Technology Cooperation Base for Digital Medical 3D Printing,Beijing 100124,China)

机构地区：[1]北京工业大学材料与制造学部激光工程研究院,北京100124 [2]北京市数字化医疗3D打印工程技术研究中心,北京100124 [3]数字化医疗3D打印北京市国际科技合作基地,北京100124

出　　处：《中国激光》2023年第16期203-212,共10页Chinese Journal of Lasers

基　　金：国家重点研发计划(2018YFE0197100)。

摘　　要：Inconel 718高温合金被广泛用于制造航天发动机等的热端零部件,提高其疲劳性能对于零部件的长期稳定服役意义重大。研究了不同热处理制度对激光选区熔化成形Inconel 718合金微观组织、相分布及疲劳性能的影响。采用电镜和电子背散射衍射仪分析了热处理试样的断口形貌、断口纵剖面应力分布及微观特征,详细阐述了热处理合金的低周疲劳断裂机理。结果表明:相较于成形态,热处理合金内部析出了δ相和γ″、γ′强化相,内部应力得以释放,疲劳性能显著提升。经过均匀化+固溶+双时效热处理后,Inconel 718合金的疲劳循环周次能够达到31990次。基于Orowan强化机制,晶粒内弥散分布的γ″、γ′强化相以及晶界上析出的δ相会阻碍位错滑移,从而延缓基体中微裂纹的扩展,增加疲劳过程中的循环周次。本次试验采用的热处理制度为激光选区熔化成形Inconel 718零部件提供了参考。Objective Inconel 718(IN718)superalloy is widely used in aerospace engines and other high-temperature components.Improving its fatigue properties is crucial for ensuring the long-term stability of the components in service.Selective laser melting(SLM)technology is one of the best choices for the manufacturing of complex aerospace components owing to its high molding rate,high design freedom,and short production cycle time.However,the rapid melting and solidification of IN718 powder during SLM leads to the precipitation of a brittle Laves phase instead of a strengthening phase,inside the component.The characteristics of layer-by-layer scanning of SLM lead to the existence of high residual stress inside SLM-fabricated parts.Therefore,heat treatment is essential.This study investigates the influence of different heat treatment processes on the microstructure,phase distribution,and fatigue properties of SLM-fabricated IN718 alloy.Methods In this study,an IN718 alloy powder was prepared using a gas atomization method with particle size distributions between 15 and 55μm.The IN718 specimens were prepared by EOSINT M280 from EOS,Germany and then cut along the plane of the substrate via wire cutting and removed.Subsequently,the IN718 specimens were subjected to three different heat treatments,as shown in Fig.2.The three heat treatments is:1)solution+double aging(SA);2)homogenization+double aging(HA);3)homogenization+solution+double aging(HSA).After heat treatment,the specimens were processed into fatigue specimens and subjected to a constant stress-controlled low-cycle fatigue test,at room temperature.Finally,after sample preparation and polishing,scanning electron microscopy(SEM)and electron back-scattered diffraction(EBSD)photographic analyses were performed.Results and Discussions The distribution of precipitated phases differs significantly after different heat treatments(Fig.5).After SA treatment,micron-levelγ″andγ′strengthening phases and a small number of distributedδphases exist in the matrix,whereas a lar

关 键 词：激光技术 激光选区熔化 Inconel 718合金 低周疲劳 热处理 

分 类 号：TG146.15[一般工业技术—材料科学与工程]