Abstract

The issues of identifying discontinuities that partially transmit ultrasonic waves are examined. Such defects are widespread in various products and welded joints of metals and plastics. Examples of “semitransparent” defects include lacks of fusion, “dead spots”, slag and other foreign inclusions in welded joints, flokens and oxide films in forgings and rolled products, etc. Moreover, even such well-studied defects as cracks can also partially transmit ultrasonic waves. However, to calculate and adjust the parameters of ultrasonic testing, hollow model reflectors (various drills, grooves, etc.), which do not transmit ultrasound, are traditionally used. The present article states that for the purposes of defect sizing, it is necessary to correctly calibrate and configure the flaw-detector–transducer kit taking into account the peculiarities of detecting defects of various types, including ones that are “semitransparent” for ultrasonic waves. To develop models of artificial reflectors imitating defects semitransparent for ultrasound, it is proposed to classify such semitransparent defects into three groups, viz., defects with filling, intermittent structures, and clogged weld. The main features of defects of these types are considered. Possible approaches to calculating the acoustic paths of ultrasonic flaw detectors when identifying defects of the three indicated types are described. It is noted that analytical and numerical methods can be used for calculating defects with filling; numerical methods should be preferred for intermittent structures; and analytical methods are better suited to defects of the clogging type.

中文翻译：

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弹性波与“半透明”缺陷的相互作用

摘要

研究了识别部分传输超声波的不连续性的问题。这种缺陷广泛存在于金属和塑料的各种产品和焊接接头中。“半透明”缺陷的例子包括缺乏熔合，“死角”，焊缝中的炉渣和其他异物，锻件和轧制产品中的絮状物和氧化膜等。此外，即使是经过充分研究的缺陷（例如裂纹）也可能部分发射超声波。但是，为了计算和调整超声波测试的参数，传统上使用不透射超声波的空心模型反射器（各种钻头，凹槽等）。本文指出，为了确定缺陷大小，考虑到检测各种类型的缺陷（包括对超声波“半透明”的缺陷）的特殊性，有必要正确地校准和配置探伤仪-换能器套件。为了建立模拟半透明缺陷的人造反射器模型，建议将这种半透明缺陷分为三类，即填充缺陷，断续结构和焊缝堵塞。考虑了这些类型缺陷的主要特征。描述了在识别三种所示类型的缺陷时计算超声探伤仪声波路径的可能方法。注意，可以使用分析和数值方法来计算填充缺陷。对于间歇结构，应首选数值方法；