摘要
目的研究超声振动对激光修复镍基高温合金梯形槽修复区显微组织及力学性能的影响,为实现高温合金的高质量激光增材修复提供参考。方法以镍基高温合金为基体和修复材料,并将超声振动引入激光增材修复过程中。采用光学显微镜,对比分析有无超声振动时梯形槽修复区的显微组织结构;采用电子背散射衍射(EBSD)、扫描电镜(SEM)、能谱仪(EDS)等设备,表征不同超声功率下梯形槽修复区的晶粒取向、析出相分布和元素组成;结合试验研究与机理分析,揭示超声振动对修复区晶粒特征和缺陷的影响规律。结果超声振动减少了梯形槽修复区底角的缺陷,修复区一次枝晶间距平均值由6.74μm减至3.38μm,晶粒平均尺寸由58.4μm降至50.2μm,等轴晶占比由46.6%增至63.4%,Laves相析出含量减少。当超声功率为4000 W时,梯形槽修复区的平均显微硬度为256.2HV0.2,相较于无超声振动时提高了17.7HV0.2。结论在超声振动作用下,梯形槽底角的熔合不良缺陷得到抑制,一次枝晶间距减小,长条状Laves相转变为颗粒状Laves相,且随着超声功率的增大,梯形槽修复区的平均显微硬度逐渐增大。
Owing to the severe service conditions,components made from nickel-based superalloys are susceptible to cracking and wear.Laser repair technology can restore the mechanical properties of damaged structural components,thereby prolonging their service life.To enhance the quality of repaired components,ultrasonic vibration has been integrated into the laser repair process to suppress defects and improve performance.The work aims to investigate the impact of ultrasonic vibration on the microstructure and mechanical properties of the trapezoidal groove repair zone in nickel-based superalloy components repaired by laser technology.Ultrasonic vibration was applied to the laser additive repair process by bottom ultrasonic device in this study.A laser beam with power of 1000 W and a spot diameter of 1.2 mm was adopted.The wire was fed with a speed of 20 mm/s at a 45°angle.The scanning speed was 10 mm/s.Following the experiments,the macro morphology and microstructure of the trapezoidal groove repair zone were observed by a Zeiss optical microscope(Axio Imager 2).The grain orientation and distribution in the trapezoidal groove repair zone were analyzed by electron backscatter diffraction(EBSD).Scanning electron microscopy(SEM,Zeiss Evo 18)and energy dispersive spectroscopy(EDS,Brukerxflash 6130)were used to analyze the distribution,morphology,and energy spectrum of the precipitated phase in the trapezoidal groove repair zone.Microhardness was measured from the top of the trapezoidal groove repair zone to the underlying matrix by a Vickers microhardness tester(HMV-2TADWXY).When ultrasonic vibration was applied,poor fusion defects at the bottom zone of the trapezoidal groove repair zone were reduced.The epitaxial growth of columnar dendrites was inhibited and the growth angle of dendrites were altered.A transition from columnar grains to equiaxed grains was observed at the top of the repair zone.The maximum multiples of uniform distribution value of the grains at the top of the repair zone reduced from 18.39 to 4.3,and the direction of grain growth shifted from the<100>to the<110>or<111>direction.Notably,the average primary dendrite spacing in the trapezoidal groove repair zone decreased from 6.74μm to 3.38μm.The average grain size reduced from 58.4μm to 50.2μm,and the proportion of equiaxed grain increased from 46.6%to 63.4%.Moreover,the precipitation of the long-strip shape Laves phase was inhibited and the Laves phase was diffusely distributed.The average microhardness of the trapezoidal groove repair zone under an ultrasonic power of 4000 W was 256.2HV0.2,indicating an increase of 17.7HV0.2 compared to the specimen under no ultrasonic vibration.The effects of ultrasonic vibration on the grain characteristics and defects of the repaired zone were discussed.The findings of this study confirm the benefit of ultrasonic vibration to the trapezoidal groove repair zone.With application of ultrasonic vibration,the poor fusion defects of the repair zone are suppressed,and the primary dendrite spacing is noticeably reduced.Furthermore,the shape of the Laves phase is transformed from a long-strip shape into a granular shape,and the average microhardness increases with an increase of ultrasonic power.
作者
姚喆赫
丁成桦
迟一鸣
王振
刘云峰
金朝龙
姚建华
YAO Zhehe;DING Chenghua;CHI Yiming;WANG Zhen;LIU Yunfeng;JIN Chaolong;YAO Jianhua(Institute of Laser Advanced Manufacturing,Zhejiang University of Technology,Hangzhou 310023,China;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,China;Key Laboratory of Special Purpose Equipment and Advanced Processing Technology of the Ministry of Education and Zhejiang Province,Zhejiang University of Technology,Hangzhou 310023,China;Suzhou Tianhong Laser Co.,Ltd.,Jiangsu Suzhou 215100,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第13期33-43,共11页
Surface Technology
基金
国家重点研发计划(2023YFB4604300)
国家自然科学基金(52175443)
浙江省自然科学基金(LD22E050013)
浙江省高校基本科研业务费项目(RF-A2023008)。
