针对目前激光熔覆层厚度无损评价的重要性,本工作结合表面超声波在介质中的传播特性对其进行测量,并在互相关函数基础上对熔覆层厚度进行了表征和评价.结果表明:随着激光熔覆层厚度的增加,表面超声波在其中的传播速率逐渐变小,在互相关函数计算微小时间差的基础上,建立了可用于评价激光熔覆层厚度的厚度-时间差关系曲线,并采用三次多项式对其进行拟合,进而得到可用于评价激光熔覆层厚度的拟合公式.最后采用不同厚度的激光熔覆层试样对拟合结果进行了验证,并同时对影响计算结果的因素进行了分析.结果表明:采用该方法对激光熔覆层厚度进行评价是可行的.%In order to settle the problem for measuring the thickness of laser cladding coating by nondestructive method, the surface acoustic wave was used according to the properties of surface acoustic wave in material. The cross-correlation function, which was usually used to calculate the difference in time of flight between two different signals, was used. The results show that the propagation velocity of surface acoustic wave in laser cladding coating is faster and faster with the thickness of coating increasing, and by using cross-correlation function for calculating the difference in time of flight, the curve between thickness of coating and difference in time of flight, which can be used to measure the thickness of laser cladding coating, is calculated, and the fitted result, which could be used to measure the thickness of coating, is obtained by using cubic polynomial. At last, the fitted result of cubic polynomial was proved by laser cladding coating with different thickness, and the influences that affected the experimental result were analyzed. The results show that the method that is represented can be used to evaluate the thickness of laser cladding coating.
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