Quality Optimization and Equivalence Evaluation of Radiographic Digital Images of Aluminum Alloy Welds in Launch Vehicles

Aiming at the problem of unclear influence of technological parameters on image quality in digital radiography (DR) of welds in carrier rocket storage tanks, 6mm(transillumination thickness)fusion welds/friction stir welds were taken as the research object. The influences of tube voltage, exposure, focus size, magnification, pixel size, integral noise reduction frame number on image sensitivity, normalized signal-to-noise ratio and spatial resolution were analyzed, which provided theoretical basis of guiding the optimization of detection process. On the basis of this, digital radiography and film photography were performed on the welds of the storage tank, and the differences in defect morphology, size, distribution, and other aspects were compared and analyzed. The results show that the image sensitivity, spatial resolution, and normalized signal-to-noise ratio of 6mm welds digital radiography results are better than the A-level technical requirements. The detection results are basically consistent with the film photography detection results, and the size measurement error is less than 3%.