厚板电子束焊缝的超声扇形扫描检测

针对传统超声斜角探伤法检测厚板焊缝宽度受限的问题,采用超声相控阵扇形扫描方法,对55 mm厚TC4电子束焊缝进行检测研究.对相控阵波束在TC4焊缝中的偏转聚焦特性及扇形扫描进行模拟分析,采用扇形扫描与D扫描、A扫描相结合的方法分析缺陷特征,给出缺陷的三维定位.结果表明：扇形扫描角度为30°～70°,采用双面检测的方法可以实现宽度有限的厚板焊缝的检测,扇形扫描图像能够更加直观地显示缺陷.在TC4电子束焊缝中检测出气孔、裂纹、未熔合和未焊透四种缺陷.通过合理设置坐标系,可以实现焊缝缺陷的三维定位,测得缺陷距离换能器楔块前沿的距离、埋藏深度和距离扫查起始位置的水平距离.

Study on ultrasonic sectorial scan of thick plate electron beam welding seam

This paper is directed at an alternative solution to the conventional ultrasonic oblique incidence testing method plagued by an inherent limitation to the detection of thick plate welding seams.This targeted solution is developed by the detection of TC4 electron beam welding seam with thickness of 55 mm using ultrasonic phased array sectorial-scan.This is coupled with a simulation analysis of deflection and focusing of ultrasonic beam and sectorial-scan in welding seam,an analysis of the characteristics of defects using the combination of sectorial-scan,D-scan,and A-scan,and above all,production of threedimensional orientation of defects.Results suggest that with scan angle varying from 30° ～ 70°,two-side sectorial-scan allows the detection of electron beam welding seam with width restriction ; sectoria-scan image enables a more intuitive display of defects.Such as pore,crack,lack of fusion and lack of penetration found in TC4 electron beam welding seam.A more reasonable development of coordinate system provides three-dimensional orientation of welding seam defect,the distance between the defect and the wedge front,and the depth and the distance between the defect and the scan starting point.