奥氏体不锈钢焊缝中的声学仿真模型与全聚焦成像检测

Acoustic simulation and total focusing method defect detection in austenitic stainless steel welds

声波在奥氏体不锈钢焊缝中传播时声束弯曲,为超声成像带来了困难。基于Ogilvy焊缝模型,建立了奥氏体不锈钢焊缝非均匀各向异性声场仿真模型,采用Dijkstra路径搜索算法对各向异性条件下的声传播路径和声传播时间进行了数值模拟和分析。在此基础上,采用Verasonics超声相控阵成像系统,进行了奥氏体不锈钢焊缝的全聚焦成像实验,采集全矩阵回波数据,并结合理论模型计算的声传播路径和相应的传播时间,进行了成像结果修正。结果表明,与均匀介质模型的全聚焦成像结果相比,基于该文模型的焊缝全聚焦成像检测结果具有更高的缺陷定位精度和分辨率,验证了该方法的可行性,为奥氏体不锈钢焊缝成像检测提供了新的思路。

Ultrasonic imaging becomes difficult due to bending of sound beam propagating in austenitic stainless steel welds.In this paper,a simulation model of anisotropic austenitic stainless steel weld soundfield was built based on Ogilvy’s weld model.The ultrasound ray path and propagation time under anisotropy were calculated and analyzed using Dijkstra’s pathfinding algorithm.In addition,an experiment based on total focusing method(TFM)was carried out using Verasonics ultrasonic phased array imaging system.Full matrix capture data was collected from the weld test block.Finally,the original TFM image was corrected based on calculation results of ray path and propagation time.The result shows that the imaging accuracy is improved,and the location error is reduced,which verify the validity of the method.The paper provides a feasible technical scheme for ultrasound defect detection of austenitic steel welds.