不锈钢焊缝中超声传播特性及TOFD检测方法研究

发布时间：2018-07-29 14:23

【摘要】：为提高对不锈钢焊缝内部缺陷的超声检测能力,开展了关于焊缝超声波传播特性及其超声衍射时差法(TOFD)的研究工作。通过调整探头间距(PCS)改变检测声束方向,分析检测声束与柱状晶夹角对检测信号信噪比的影响,提出基于超声TOFD技术的焊缝一次波、二次波检测方法;鉴于二次波检测中特征波结构的复杂性,建立了特征波传播模型以识别二次波特征信号。研究结果表明,焊缝中传播的超声波声束呈现明显的各向异性特征,柱状晶与检测声束的夹角是检测信噪比的关键影响因素;与探头置于焊缝根部侧和余高侧相对应,需分别采用一次波和二次波检测方法进行TOFD检测;当检测声束与柱状晶夹角在35°~48°且检测区域具有较高声压时,可有效提高对焊缝缺陷的检测能力。基于声波传播的各向异性特征提出的超声TOFD一次波和二次波检测方法对于提高奥氏体不锈钢焊缝的超声检测能力具有重要作用。
[Abstract]:In order to improve the ultrasonic detection ability of stainless steel welds, the ultrasonic propagation characteristics of stainless steel welds and the ultrasonic diffraction time difference method (TOFD) were studied. By adjusting probe spacing (PCS) to change the direction of detecting sound beam and analyzing the influence of the angle between detection sound beam and columnar crystal on signal signal-to-noise ratio (SNR) of the detected signal, a new method of weld seam primary wave and secondary wave detection based on ultrasonic TOFD technology is proposed. In view of the complexity of the characteristic wave structure in the secondary wave detection, the characteristic wave propagation model is established to identify the secondary wave characteristic signal. The results show that the ultrasonic beam propagates in the weld shows obvious anisotropic characteristics, the angle between the columnar crystal and the detected sound beam is the key factor affecting the detection of SNR, which corresponds to the probe placed at the root side of the weld and the residual high side. It is necessary to use the primary wave and the second wave to detect the TOFD. When the angle between the detection beam and the columnar crystal is 35 掳~ 48 掳and the detection area has a high sound pressure, the detection ability of weld defects can be improved effectively. The ultrasonic TOFD primary and secondary wave detection methods based on the anisotropic characteristics of acoustic propagation play an important role in improving the ultrasonic detection ability of austenitic stainless steel welds.
【作者单位】：南昌航空大学无损检测技术教育部重点实验室;
【基金】：国家自然科学基金(11664027,11374134)资助项目
【分类号】：TG441.7

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