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利用放射线进行无损探伤,是众所周知的。例如工业 X 光透射照相探伤,γ射线透射照相探伤等。由于透射照相探伤法有许多优点,它就成为目前广泛应用的探伤方法之一。但是,照相法对于在100毫米以上厚度的工件,由于透过工件后的射线强度变得很微弱,照相底片需要长时间曝光,因此很难检查厚度达到200毫米的工件。即使利用射线能量较强的放射性同位素 Co~(+60),曝光时间仍然很长。例如,用5克镭当量的Co~(60)射线源,检查150毫米厚的钢制件,曝光时间需要1～4小时之久,且灵敏度较低,一般在3%,有的甚至只能达到5%。在探伤速度要求快,灵敏度要求高的情况下,仅用照相法就很难满足要求。近十多年来,随着
The use of radiation for nondestructive testing is well known. Such as industrial X-ray transmission photographic flaw detection, gamma ray transmission photographic flaw detection. Because of the many advantages of transmission photogrammetry, it has become one of the most widely used methods of detection. However, the photographic method is difficult to inspect workpieces up to a thickness of 200 mm for workpieces with a thickness of 100 mm or more, since the intensity of the radiation after passing through the work piece becomes very weak and the photographic film needs a long time exposure. Even with the radioactive isotope Co + (+60), the exposure time is still long. For example, with a 5-gram radium Co 60 radiation source, inspection of 150 mm thick steel parts takes about 1 to 4 hours for exposure and low sensitivity, typically 3%, and sometimes even only Reached 5%. In the detection of fast speed, high sensitivity requirements of the situation, only the photographic method is difficult to meet the requirements. In the past ten years, with