【作者】 郑超； 季忠； 宋立彬； 栾贻国；

【Author】 Zheng Chao;Ji Zhong;Song Li-bin;Luan Yi-guo;Shandong University;

【机构】 山东大学；

【摘要】 针对激光冲击微冲孔工艺中的晶粒尺度效应问题,利用影像测量仪和扫描电镜检测了紫铜箔材不同初始晶粒尺寸时的微孔轮廓精度及断面形貌,分析了初始晶粒尺寸对微孔成形质量的影响规律。实验结果表明,在相同激光功率密度时,随初始晶粒尺寸增大,圆度误差均增大,微孔轮廓精度降低;增强激光功率密度能在一定范围内提高微孔轮廓精度,但在初始晶粒尺寸近似等于箔材厚度条件下的轮廓精度反而变差。与准静态微冲孔工艺获得的微孔断面形貌不同,高应变率下微孔断面由圆角、剪切区和毛刺组成;随初始晶粒尺寸增大,圆角和毛刺均增大,剪切区比例减小,断面质量恶化;增强激光功率密度并未明显改善微孔的断面质量,说明初始晶粒尺寸对微孔断面质量起主导作用。更多还原

【Abstract】 Influence of initial grain size on forming quality, characteristic of contour accuracy and fracture morphology was investigated experimentally with image measuring instrument and SEM. The pure copper foils were first annealed at different temperatures to obtain microstructures with different grain sizes. The results show that the initial grain size has a noticeable effect on forming quality of punched holes. The roundness became worse with the increase of initial grain size resulting in the decrease of contour accuracy under the same laser power density. While the laser power density was enhanced, the contour accuracy of punched holes can be improved except for the case in which the ratio of initial grain size to foil thickness is approximately equal to 1. Unlike the fracture morphology in the quasi-static loading conditions, the fracture surface of punched holes at high strain rates consisted of rollover, shearing zone and burr. As the initial grain size became larger, the depths of rollover and burr increased while the shearing depth diminished, indicating the fact that the surface quality deteriorated. It was found that the surface quality was not evidently improved, suggesting that the initial grain size plays a dominant role in the surface quality of punched holes.更多还原