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对于薄板(3毫米)焊缝超声波探伤,目前国内尚未标准可以参照。采用普通斜探头,由于发射声脉冲受探伤仪放大迟滞特性的影响,薄板焊缝中的缺陷回波往往淹没在发射脉冲中,不易分辨。双晶直探头可以用于探测平板的近表面缺陷,但不能探测焊缝的缺陷。双晶斜探头综合了上述二种探头的特点,既可以象普通斜探头那样,探测焊缝中的缺陷,又可以克服放大迟滞特性的影响,使缺陷回波清晰。另外,双晶斜探头还可以根据工件中声程的要求,设计倾斜角和入射角,使得探头焦距在声程之内,达到最佳的探伤效果。本文对双晶斜探头的主要参数提出设计依据。根据设计制作的探头,用于民用液化煤气罐焊缝超声波探伤,获得满意的效果。
For sheet (3 mm) weld ultrasonic flaw detection, at present there is no standard can refer to. The use of ordinary oblique probe, due to the emission sound pulse flaw by the flaw detector hysteresis characteristics of the flaw welds in the flaw welt often submerged in the launch pulse, not easy to distinguish. Dual crystal straight probe can be used to detect near-surface defects flat, but can not detect the weld defects. The double crystal oblique probe integrates the characteristics of the above two probes, which can not only detect the defects in the welding seam but also overcome the influence of the amplification hysteresis characteristic to make the echo of the defect clear. In addition, the twin crystal oblique probe can also design the tilt angle and the incident angle according to the requirements of the acoustic path in the workpiece, so that the probe focal length is within the acoustic path and the best detection effect is achieved. In this paper, the main parameters of bi-crystal oblique probe proposed design basis. According to the design of the probe, used for civilian liquefied gas tank weld ultrasonic testing, to obtain satisfactory results.