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为了优化厚壁焊缝尤其是奥氏体焊缝的超声检测条件,对焊缝和母材中超声传播特性进行研究。实验研究了焊缝和母材中的超声衰减系数随探头频率的变化规律,以及探头的K值对检测结果的影响,并研究了焊缝和母材中超声的频散规律,以及声速和衰减的各向异性。研究结果表明,焊缝中声速小于母材,而衰减系数是母材的数倍,并且焊缝中频散严重。提出了合理的超声检测条件:选择K值尽量小的窄脉冲纵波斜探头,探头频率1~2 MHz,并且要保证探头具有足够的接收灵敏度和带宽,检测位置的确定应尽量减小焊缝中声程。
In order to optimize the ultrasonic testing conditions of thick-walled weld, especially austenitic weld, the ultrasonic propagation characteristics in weld and base metal were studied. Experimental study of the weld and the base metal ultrasonic attenuation coefficient with the probe frequency changes, as well as the probe K value of the test results, and study the weld and the base metal ultrasonic dispersion law, as well as the sound velocity and attenuation Anisotropy. The results show that the acoustic velocity in the weld is less than the base metal, and the attenuation coefficient is several times that of the base metal, and the dispersion of the weld is serious. A reasonable ultrasonic testing condition is proposed as follows: a narrow-pulse longitudinal wave oblique probe with K value as small as possible is selected, the probe frequency is 1 ~ 2 MHz, and the probe has sufficient receiving sensitivity and bandwidth. The detection position should be minimized in the weld Sound path.