Aiming at the film cooling holes machining of nickel-based single crystal material by picosecond ultrashort pulsed laser, physical depth of field microscope is used to determine the geometry of the film cooling holes, meanwhile the cavity lumen surface of the membrane pore is observed by optical microscopy. Performances of porous film samples prepared by two processes of picosecond ultrashort pulsed laser and electric discharge using high temperature and low cycle fatigue equipment are compared, and specimen fracture is analyzed by scanning electron microscope (SEM) to evaluate the performance. The results show that the entering and exiting holes surface can avoid ablation by picosecond ultrashort pulsed laser processing step by step and effective control of energy density. While the geometric accuracy can meet the design specifications, also there is no remelting layer, intermittent beads,arcing and micro-cracks and other defects in the cavity. Besides, the surface integrity of the film holes after processing could be effectively improved. The comparative tests of high temperature low cycle fatigue performance of picosecond ultrashort pulsed and EDM film show that the cycle number of sample perforated by picosecond ultrashort pulsed laser is as many as three times that of EDM. SEM of high temperature low cycle fatigue fracture shows that the two kinds of processing specimens are cleavage fracture, without metallurgical defect, the remelting layer formed by EDM drilling may contribute to the fracture, and there is no obvious remelting layer in ultrashort pulsed laser drilling.
基金资助:国家科技重大专项课题(2014ZX04001041)。
作者简介: 刘瑞军:高级工程师,主要从事超短脉冲激光加工研究工作。
引用本文:
刘瑞军,桓恒,李伟剑,李光泽,韦廷立,马永跃. 镍基单晶材料皮秒级超短脉冲激光气膜孔加工表面完整性研究[J]. 航空制造技术, 2018, 61(15): 84-90.
LIU Ruijun, HUAN Heng, LI Weijian, LI Guangze, WEI Tingli, MA Yongyue. Research on Surface Integrity of Ni-Based Single Crystal Materials in Picosecond Ultrashort Pulsed Laser Gas Films. Aeronautical Manufacturing Technology, 2018, 61(15): 84-90.