基于超声无损评价的表面粗糙度测量方法

A Surface Roughness Measurement Method Based on Ultrasonic Nondestructive Evaluations

选用不同线切割工艺制备各种表面粗糙度的304不锈钢试块。基于超声波入射到粗糙表面的自由应力边界条件,采用表面回波的幅值均值、离差率和平均功率同时表征粗糙度,根据主成分分析法建立粗糙度的多参数评价模型。实验结果表明,和触针法相比,超声评价法误差最大为3.09%,且其不确定度更低,将该模型用于含粗糙表面试块的晶粒尺寸评价中,评价误差小于5%,可见该方法能有效实现表面粗糙度及材料微观结构的一体化评价,可提高超声自动化评价系统的实用性。

Different thread cutting processes were used to prepare a set of 304 stainless steel blocks with different surface roughness. Based on boundary conditions, the mean amplitude, the rate of standard deviation and the average power of the surface echo were simultaneously used to characterize the roughness, a multi-parameter evaluation model dependent on surface roughness was established using PCA. Compared with the needle contact method, the experimental results show that the maximum error of the surface roughness measured by ultrasonic is as 3.09% and its uncertainty is lower. Moreover, the errors are no more than 5% of grain size evaluation when applied the surface roughness evaluation model. Thus the proposed method may realize integrative evaluation of surface roughness and microstructure to improve the applicability of ultrasonic automatic evaluation.