用数值计算技术和试错法确定金属材料表面对激光的吸收率

DETERMINATION OF LASER ABSORPTIVITY OF METAL BY NUMERICAL CALCULATION TECHNIQUE AND TRIAL-AND-ERROR METHOD

提出了一种激光重熔条件下确定金属材料激光吸收率的方法．通过改变输出功率，控制试样表面状态，利用计算机数据采集系统对激光表面重熔的试样进行定点温度采集；按不同表面状态假定材料对激光的吸收率，采用经过验证的激光表面重熔数值模拟程序计算温度场并与实测结果对比，以试错法修正所假定的吸收率，确定了ＤＬ３１合金表面对激光的吸收率．与文献中实验得到的吸收率值较为接近．用所测吸收率值计算不同功率条件下试样定点温度的变化，与实测温度变化规律基本吻合．

A method of determining the laser absorptivity of metallic surface is presented. Under changing power to control the state of the surface of sample (solid state or liquid state), the temperature at a certain point in the sample is measured and treated by using a computer data acquisition system. The temperature field in the sample is calculated by a simulation software of laser surface remelting under an assumed absorptivity. Then the assumed absorptivity was adjusted and the numerical calculation is repeated again until the calculated result is coincident with experimental one. The obtained absorptivity of the DL31 alloy surface is in good agreement with that in a literature. Using the obtained value of the absorptivity, the temperature-time curves calculated at a certain point under different conditions are basically coincident with experimental ones.