摘 要
鉴于小径薄壁管对接环焊缝超声波检测难题——普通探头超声盲区大于壁厚范围，小径管道内外壁的几何散射引起超声波反射衰减大等。本文从探头着手，采取有效的聚焦方法，选择合适的探头频率、晶片尺寸、晶片曲率设计合理探头楔块，使用适当的楔块材料及晶片材料，使研制的探头具有足够灵敏度，小于2.5mm的始波占宽、短前沿（≤5mm）、分辨力高、杂波少、表面波分量少，适宜于小径薄壁管道对接环焊缝的超声定量检测。
为了解决这种特殊探头的各种相关技术指标的测试，本文还设计了几种特殊试块及相关的反射体。
这种探头通过试用与验证，符合实际需要，取得良好效果，基本解决了在役薄壁管超声波检测代替射线检测的难题。
关键词：小径薄壁管，聚焦探头，始波占宽，短前沿，自身高度
Abstract
Considering the difficulties in ultrasonic testing of butt weld of thin-walled tube with small dimension, the present paper starts with the probe. The difficulties are mainly the dead zone of common probe which is beyond the confine of wall thickness, the big echo attenuation of ultrasonic testing due to geometrical scatting of internal and external wall of pipe with small dimension, etc. In this paper, the effective focusing methods are taken; the proper probe frequency, crystal dimension and curvature are selected; the reasonable probe wedge is designed; and the appropriate wedge and crystal materials are used. So the investigated probe has many advantages, such as, enough sensitivity, initial pulse width less than 2.5 mm, short front distance (≤5mm), high resolution, a spot of clutter, a little surface wave component, which is suitable for the quantitative ultrasonic testing of butt weld of thin-walled tube with small dimension. To solve the testing of relative technical indicators of this special probe, this paper investigates some test blocks and the relative reflectors.
According to the trial and confirmation, it meets the actual demand and is well-tried. It is proven that the difficulties in ultrasonic testing of butt weld of thin-walled tube with small dimension come to a basic settlement.
Keywords: Thin-walled tube with small dimension; Focusing probe; Initial pulse width; Short front distance; Indicated defect length.
目 录
1 引言………………………………………………………………………………………1
2 设计思想 ………………………………………………………………………………2
2.1 使用目的及主要性能要求 ……………………………………………………………2
2.2 探头参数的选择 ………………………………………………………………………3
3 探头性能及参数的确定 ……………………………………………………………9
4 系列探头的组成 ……………………………………………………………………10
5 探头性能的测试 ……………………………………………………………………11
5.1 定位准确性的测试……………………………………………………………………11
5.2 探头前沿………………………………………………………………………………11
5.3 K值测试…………………………………………………………………………… 11
5.4 距离波幅曲线的形状 ………………………………………………………………12
6 特殊标准试块的设计和使用 ……………………………………………………13
6.1 标准反射体……………………………………………………………………………13
6.2 辅助反射体……………………………………………………………………………13
6.3 试样的使用……………………………………………………………………………13
7 试验与验证 …………………………………………………………………………16
7.1 试管根部未焊透测高精度验证试验…………………………………………………16
7.2上海石化总厂管线检评试用验证 ……………………………………………………20
8 结论 ……………………………………………………………………………………21
参考文献 ………………………………………………………………………………22
致谢 ………………………………………………………………………………………23
