Revision of Ultrasonic TOFD Image of Stainless Steel Weld Based on WPT Decomposition
-
摘要: 将超声衍射时差法(超声TOFD)应用于奥氏体不锈钢焊缝的无损检测中,分析了焊缝组织对超声TOFD检测信号的影响;基于小波包分解技术的时频分析特性,对检测信号进行三层分解,并获得了适用于灰度成像的分解信号.结果显示:受焊缝组织结构的超声散射影响,检测图像不但存在相当程度的波纹干扰,而且其缺陷特征图像也出现了较严重的形状扭曲;选择合适的小波包分解信号可在保持时间分辨率的同时抑制噪声,基于重构信号进行灰度成像能够提高检测图像的质量并避免缺陷图像的扭曲.Abstract: Ultrasonic Time of Flight Diffraction method (U-TOFD) is adopted in testing the defects of austenitic stainless steel weld,and the influences caused by the weld structure are analyzed.Besides,the testing signal is decomposed by wavelet packed method (WPT) and the decomposed signal that fits for gray imaging is obtained.The results indicate that there are amount of noise stripes and shape torsion in the gray imagery because of the ultrasonic scattering caused by the column grain in weld,the noise level can be restrained without destroying the time resolution through choosing suitable decomposed signal.Eventually,gray imaging based on the decomposed signal is beneficial for improving the quality of testing signal and avoiding the torsion of the defect′s imagery.
-
Keywords:
- Ultrasonic TOFD /
- Gray imaging /
- Wavelet packet /
- Stainless steel weld /
- Noise
-
-
[1] 周杨,梁春雷.制氢装置中变气系统奥氏体不锈钢设备失效问题分析[J].石油化工设备技术,2013,34(4):31-37. [2] 张鹰,张延丰,雷毅.奥氏体不锈钢焊缝的超声波检测方法研究[J].无损检测,2006,28(3):119-122. [3] 孙咸.不锈钢焊缝金属的组织演变及其影响[J].机械制造文摘,2012(6):6-10. [4] BALASUBRAMANIUM T,BABY S,PARDIKAR R J.Time-of-flight diffraction technique for accurate sizing of surface breaking cracks [J].Insight,2003,45(5):600-604. [5] BASKARAN G,BALASUBRAMANIAM K,LAKSHMANA R C.Shear-wave time of flight diffraction (S-TOFD) technique[J].NDT & E International,2006,39(6):458-467. [6] 林莉,杨平华,张东辉.厚壁铸造奥氏体不锈钢管道焊缝超声相控阵检测技术概述[J].机械工程学报,2012,48(4):12-18. [7] 盛朝阳,刚铁,迟大钊.基于分水岭方法的超声TOFD检测图像分割[J].机械工程学报,2011,47(8):35-40. [8] 毛秉毅.基于分离谱技术的自适应带通滤波法在超声检测中的应用[J].仪器仪表学报,2006,27(6):1390-1391. [9] 齐爱玲,刘涛,马宏伟.基于小波变换的焊接缺陷超声信号处理[J].仪器仪表学报,2006,27(6):1390-1391. [10] CHEN Han-xin,ZUO Ming J,WANG Xiao-dong,et al.An adaptive morlet wavelet filter for time-of-flight estimation in ultrasonic damage assessment [J].Measurement,2010,43:570-585. [11] 罗雄彪,陈铁群,万英.超声检测信号中的小波包分析[J].机械工程学报,2006,42(4):142-146. [12] 孙晓娜,雷毅,张鹰.厚板奥氏体不锈钢焊缝显微组织分析[J].金属热处理,2006,31 (10):21-23.
计量
- 文章访问数: 0
- HTML全文浏览量: 0
- PDF下载量: 0
下载:
