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.
