用扫描白光干涉术检测合金韧窝断口微观三维形貌

摘要

运用扫描白光干涉法对30CrMnSiA合金韧窝断口复杂的三维表面微观形貌进行了检测.系统采用Linnik干涉结构,并通过基于扫描空间余弦傅里叶频域分析的算法重建断口表面三维形貌.实验中扫描行程达120 μm,纵向检测精度优于5 nm,余弦傅里叶分析表现出很强的位相提取和噪声抑制能力,韧窝断口微观形貌的三维重建效果理想.采用小岛法对获得的三维形貌数据进行分形维数测算,在40%～70%相对切割高度处,断口表面分形维数为1.630 4～1.643 2,平均值为1.641 7,标准差为0.012 0.结果显示,30CrMnSiA合金韧窝断口微观形貌具有典型的分形特征.实验表明,扫描白光干涉术是检测断口微观三维形貌的一种有效方法,具有纵向精度高,测程范围大,重构效率高等特点.%Scanning White-light Interferometry (SWLI) was proposed to measure the complex microscopic surface topography of a dimple fracture of 30CrMnSiA alloy. The Linnik structure was adopted in the system and the 3D image of the dimple fracture was rebuilt by the cosine Fourier analysis algorithm. Experiments show that the longitudinal measuring accuracy is better than 5 nm for a scan range of 120 μm. The cosine Fourier analysis offers strong abilities of phase extraction and noise suppression, and an ideal 3D reconstruction image of the dimple fracture is obtained. The obtained surface data were tested for fractal dimension by a slit island method. At incised height from 40％ to 70％, the fractal dimension values range from 1. 630 4 to 1. 643 2 with an average of 1. 641 7 and the standard deviation of 0. 012 0, which indicates that the dimple fracture of 30CrMnSiA has a typical fractal character. In conclusion, the SWLI is an effective way to measure the microscopic 3-D fracture surface topography,and it is characterized by high longitudinal precision, long dynamic measuring range and high reconstruction efficiency.