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利用文献所介绍的原位法并加以改进 ,测定了铝合金表面呈固态和液态时对激光的吸收率。实验结果表明 ,试样的表面状况对激光吸收率有重要影响 ,激光功率对吸收率的影响甚小 ,但对表面涂黑的试样 ,激光功率过高会使涂层烧损而降低吸收率。当试样表面出现熔池时 ,所测得的吸收率是激光斑点中液态表面和固态表面的综合平均值 ,真实的液态吸收率需用实测与数值模拟相结合的方法求取。当激光入射角在 0°～ 45°范围时 ,无论是固态试样还是出现熔池 ,其吸收率均随入射角的增大而线性增加。文中对实测数据的回归处理方法亦做了改进 ,先将较复杂的曲线方程转换成直线方程 ,然后进行线性回归处理。
The in situ method introduced in the literature was used to improve the absorption rate of the laser when the surface of the aluminum alloy was in solid state and liquid state. The experimental results show that the surface condition of the sample has an important influence on the laser absorption rate, and the laser power has little effect on the absorption rate. However, for the sample with the black surface, the laser power is too high, . When the weld pool appears on the surface of the specimen, the measured absorptivity is a composite average of the liquid surface and the solid surface in the laser spot. The real liquid absorptance should be obtained by a combination of actual measurement and numerical simulation. When the angle of incidence of laser is in the range of 0 ° ~ 45 °, the absorption rate increases linearly with the increase of incident angle, no matter it is a solid sample or a pool appears. In this paper, the regression processing method of measured data has also been improved. First, the complex curve equation is transformed into a straight line equation, and then linear regression processing is performed.