摘要
多激光粉末床熔融(ML-PBF)采用多束激光并行加工,是提高制造效率和大尺寸零件整体化增材制造的有效方法。但不同的激光束实际工作时参数难以保持一致,特别是激光功率会存在偏差,其中多激光搭接区最为关键。笔者通过设置4组差值为10、20、30、40 W的激光功率组合,探究了激光功率对ML-PBF制备的GH3536镍基高温合金搭接区组织和性能的影响。结果表明:成形试样的致密度最高可达99.6%,但搭接激光功率增大不仅会导致致密度降低至99.3%,孔隙率超过0.08%,还会导致γ相的衍射峰向大角度偏移,晶格常数降低。同时,随着搭接激光功率增大,搭接区内的晶粒尺寸由14.57μm增大至17.23μm,大角度晶界占比由36.66%上升至55.91%。搭接区内残余应力随着搭接激光功率的增大而先降低后升高,在激光功率相差30 W时降至最低值43.8 MPa。搭接区硬度随着搭接激光功率的增大而降低,由297.3 HV3降低至291.1 HV3。4组激光功率组合下制备的试样的极限抗拉强度在792.9~830.9 MPa范围内,当激光功率相差10 W时强度达到最高值,延伸率为23.7%。增大搭接激光功率会降低ML-PBF的熔凝稳定性并增大温度梯度,进而对搭接区内的微观组织、残余应力以及零件的力学性能产生影响。
Objective Multi-laser powder bed fusion(ML-PBF)has been widely used in the aerospace,biomedical,and automotive marine industries owing to its high efficiency.ML-PBF equipment consists of multiple energy and scanning systems,such as lasers,galvanometers,F-theta lenses,and other optics.Because the pump source is converted into pump light and then amplified by the gain medium and resonant cavity to form a laser output,there may be deviations in the laser power among multiple lasers.Meanwhile,the power degradation after continuous operation differs.Transmission of a laser beam through an optical path causes different energy losses.Therefore,it is difficult to ensure that each laser beam has the same power during the ML-PBF process.Therefore,this study focuses on the effect of power deviations on the forming quality of a GH3536 nickel-based superalloy using ML-PBF.The metallurgical defects in the overlap region,microstructure,and residual stress characteristics are analyzed by setting up different laser power groups.This study aims to lay a theoretical and technical foundation for ML-PBF to form high-performance large-sized parts.Methods Self-developing ML-PBF equipment was used in this study,and gas-atomized GH3536 nickel-based superalloy powder was measured and found to have a size distribution of 11.2-66.9μm.Each group of specimens was first scanned on one side using the optimal laser power(240 W),and the other side was scanned at 250,260,270,and 280 W.The width of the overlap regions of the four specimen groups was 150μm.First,three specimens with dimensions of 4 mm×4 mm×5 mm were machined from the vicinity of the overlap regions of each specimen using wire electrical discharge machining.The relative densities of the specimens were measured using the Archimedes?principle.After grinding with 400-3000 grit sandpaper and mechanical polishing,the internal pores and cracks were observed using an optical microscope(Leica DM750M,Germany),and the porosity was calculated using Image J software.After etching with A2 ele
作者
沈沐宇
谢寅
李继康
蔡超
滕庆
魏青松
Shen Muyu;Xie Yin;Li Jikang;Cai Chao;Teng Qing;Wei Qingsong(State Key Laboratory of Materials Processing and Die&Mould Technology,School of Materials Science and Technology,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第24期117-126,共10页
Chinese Journal of Lasers
基金
国家自然科学基金(52201040,52275333)
中国博士后科学基金项目(2021M701291)
湖北省科技厅2020省重点研发计划(2020BAB049)
中国航空制造技术研究院稳定支持项目(KZ571801)。
关键词
激光技术
多激光粉末床熔融
增材制造
激光功率
搭接区
镍基高温合金
微观组织
残余应力
力学性能
laser technique
multi-laser powder bed fusion
additive manufacturing
laser power
overlap region
nickel-based superalloy
microstructure
residual stress
mechanical properties
