激光窄条喷丸成形的实验研究

利用短脉冲激光对LY12CZ航空铝合金进行了窄条激光喷丸(LP)成形。激光脉冲参数:波长为1.06μm,脉冲宽度为23 ns,光斑直径为7 mm,输出能量为22 J。试样外形尺寸为100 mm×25 mm×2 mm,喷丸窄条宽度为7 mm,条带内相邻光斑的距离为4 mm,相邻喷丸条带中心间距为15 mm。利用弧高仪测试样变形后的变形量,用X-350A残余应力测试仪测其残余应力,用HVS-1000硬度计测其显微硬度和用Taylor Hobson-5M测表面粗糙度。实验结果表明,试样经激光喷丸后,变成了曲率半径为1.87 m的单曲率件,冲击硬度得到提高,喷丸条带内的表面粗糙度值增大,但仍然保持光滑,试样上下表面的残余应力均有显著提高,其激光喷丸面的残余应力平均增加了250%,下表面平均增加了75%,喷丸条带内的硬度平均值增加约40%。

Experimental Research on Narrow Strip Laser Peening Forming

The aeronautic aluminum alloy LY12CZ was taken as an example for narrow strip laser peening (LP) by Nd∶glass laser. In the experiments, the laser parameters were: wavelength 1.06 μm, pulse duration 23 ns, laser spot diameter 7 mm and output energy 22 J. The sample size was 100 mm×25 mm×2 mm, the width of the narrow strip was 7mm, its surface was coated with black paint, and its laser peening zone was six parallel narrow strips with adjacent central interval 15 mm. In each narrow strip, the distance between adjacent laser spots was 4 mm. The deformation of specimen after laser peening was measured with an arc height measurement, the microhardness with HVS-1000 tester and the residual stress with X-350A XRD tester. The results indicate that after laser peening the curvature radius of specimen after laser peening is 1.87 m, the peened surface of narrow strip has a larger roughness but still keeps smooth, and that the magnitude of residual stress on both surfaces increases distinctly. The laser peened surface residual stress is increased averagely by about 250%, the residual stress of undersurface is increased averagely by 75%, and the microhardness of laser peened zone is improved by 40%.