目前国外在焊缝超声探伤中,大多采用折射角β为整数值的探头。折射角的测定及探伤时萤光屏上时间扫描线的调整,都使用国标焊接协会(IIW)推荐的试块。这一整套方法必需使扫描线读数代表声波在工件中传播的实际声程,因此缺陷的定位是以数学上的极座标为基础的。但是实际上对于平面的或接近平面的工件,需要测定的是缺陷埋藏的深度(垂直距离)和缺陷与探头入射点之间的水平距离,也就是需要用数学上的纵座标来定位,因此必须将极座标换算成纵座标。这就需要通过三角函数的计算,为了计算上的方便, At present, foreign ultrasonic flaw detection in the weld, mostly using the angle of refraction β is the integer value of the probe. The determination of refraction angle and detection time line scanning fluorescent screen adjustment, use the National Standard Welding Association (IIW) recommended test block. This whole set of methods must make the scan line readings represent the actual acoustic path of the sound waves propagating in the work piece and therefore the positioning of the defect is based on a mathematical polar coordinate. In practice, however, for planar or near-planar workpieces, the depth (vertical distance) at which the defect is buried and the horizontal distance between the defect and the point of incidence of the probe, that is, where the mathematical ordinate is required, Polar coordinates must be converted into the vertical coordinate. This requires the calculation of trigonometric functions, in order to calculate the convenience,