LPBF成形新型定向凝固镍基高温合金基础工艺研究  

Basic Process of New Directional Solidification Nickel-Based Superalloy Fabricated by Laser Powder Bed Fusion

作　　者：周润森 魏恺文 梁静静[2] 陈佳 李高航 屈亮 刘梦娜 李祥友 孙晓峰[2] 曾晓雁 Zhou Runsen;Wei Kaiwen;Liang Jingjing;Chen Jia;Li Gaohang;Qu Liang;Liu Mengna;Li Xiangyou;Sun Xiaofeng;Zeng Xiaoyan(Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,Liaoning,China)

机构地区：[1]华中科技大学武汉光电国家研究中心,湖北武汉430074 [2]中国科学院金属研究所,辽宁沈阳110016

出　　处：《中国激光》2023年第24期152-162,共11页Chinese Journal of Lasers

基　　金：国家科技重大专项(Y2019-VII-0011-0151);中央高校基本科研业务费专项资金(2021XXJS029)。

摘　　要：研究了激光粉末床熔融(LPBF)增材制造技术成形新型定向凝固镍基高温合金ZGH451的致密化行为、显微组织和凝固晶粒取向。结果表明:未熔合和凝固裂纹是主要冶金缺陷;通过增大激光功率、减小扫描间距和扫描速度,可以有效消除未熔合缺陷;在激光功率150 W、扫描层厚0.02 mm、扫描速度600~800 mm/s、扫描间距0.06~0.08 mm的工艺窗口内,可以获得无裂纹、高致密(致密度为99.9%)样品,其凝固组织主要由基本沿构建方向定向生长的柱状晶构成,具有典型的微细枝晶显微组织,一次枝晶间距小于1μm,二次枝晶不发达。枝晶间存在TiC和TaC颗粒析出,未观察到明显的γ/γ′共晶。样品呈现出一定的定向凝固特性,[001]织构明显,但相邻熔道搭接区域内仍有复杂热流产生的大取向差柱晶。样品力学性能优异,其屈服强度与传统定向凝固工艺制备的第三代单晶高温合金相当。研究结果证实了采用LPBF技术成形定向凝固ZGH451镍基高温合金的可行性。Objective The traditional directional solidification process has made outstanding contributions to improving the thermal-mechanical fatigue performance and service cycle of turbine blades.However,the traditional directional solidification process has limitations.It not only hampers the formation of new generation of turbine blades with complex cooling structures,but also results in a coarse microstructure and microporosity,along with γ/γ′eutectic.These issues restrict further development of directional solidification turbine blades.Laser powder bed fusion (LPBF) technology can form almost any complex shape of metal components.Meanwhile,LPBF technology has an extremely high cooling rate (10~3?10~6 K/s) and temperature gradient (10~3?10~5 K/s),which is expected to eliminate the above-mentioned defects and form a finer microstructure.In this study,the densification behavior,microstructure,and solidification grain orientation of a new directionally solidified nickel-based superalloy,ZGH451,fabricated using LPBF are investigated.The feasibility of using LPBF technology to form a directionally solidified nickel-based superalloy,ZGH451,is confirmed.Methods A self-developed LPBF equipment is used for ZGH451 experiments.The equipment includes a fiber laser with a spot diameter of approximately 80μm.Cubes measuring 10 mm×10 mm×5 mm are produced on 45#cast steel plates.Optical micrographs (OM) are collected using a optical microscope.The microstructures of the samples are observed using a scanning electron microscope (SEM).An SEM with electron backscattered diffraction (EBSD) is used to characterize the grain morphology and orientation characteristics.The EBSD scanning step is performed at 1.5μm.The final calibration rates are all greater than 95%.The inter-dendritic precipitates of the samples are analyzed using a transmission electron microscope (TEM).The tensile specimens are tested on a high-precision electronic universal testing machine at a constant drawing rate of 2 mm/min.Results and Discussions This study s

关 键 词：激光技术 激光粉末床熔融 定向凝固镍基高温合金 冶金缺陷 显微组织 

分 类 号：TG146.1[一般工业技术—材料科学与工程]