射线检测小径管时, 在底片上呈现的黑度差非常大, 严重影响缺陷检出结果的可靠性。为此, 对 42 mm×5 mm的16MnR钢管进行了射线透照参数的理论分析。通过试验, 得出在曝光量不变、管电压变化时, 以及管电压不变、曝光量变化时的射线检测对比试验效果。试验证实, 管电压或曝光量不足都会引起胶片的曝光不足, 导致影像黑度值降低; 但是当管电压或曝光量过高时, 将引起影像质量的降低, 不利于缺陷的检出。只有当曝光量和管电压达到合适值, 才能得到良好的细节影像, 保证射线检测效果。

The density value of film varied very much when testing small diameter tube by radiographic testing, which affected the reliability of defect detecting. For this reason, the radiographic testing parameters were analyzed for a  42 mm×5 mm 16MnR steel theoretically, then the sensitivity comparison testing were made on two kinds of situations with constant exposure and changing voltage, and also constant voltage and changing exposure . Testing results showed that, lower voltage and exposure would lead inadequate exposure on the film and cause lower density. But too high exposure would cause the reduction of image quality, so had not conducive to defect detection. Only when the exposure and tube voltage achieved an appropriate value, the good details of images could be obtained, and the radiographic testing effect could be assured.