The Examination of Discontinuities in Welds by Stereoradiography.
ARMY CONSTRUCTION ENGINEERING RESEARCH LAB CHAMPAIGN ILL
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Since welds are rarely defect-free, it is desirable to quantify the effects of defects on the mechanical properties of welds and to develop a field inspection procedure more reliable, more complete, faster, and less costly than that currently in use. This investigation of the feasibility and practicability of stereoradiography was to satisfy the latter objective. Stereoradiography, unlike normal incidence radiography or ultrasonic inspection, permits direct three-dimensional observation of internal flaws. Stereoradiography entails obtaining an x-ray exposure at two known positions of the object with respect to the x-ray tube and viewing the stereo-pair through a stereo-viewer stereoscope. By accurately measuring the parallax differences resulting from the specimen or x-ray tube shift, one may calculate the weld flaws depth below the plate surface using photogrammetric principles. To evaluate this technique, ten pores in a defective weldment were measured at three different times. The results were compared to determine how well an observer could reproduce his measurements. The weld was sectioned, and the actual pore depths were measured directly. These results were compared to the stereoradiographically-measured depths to determine the accuracy of the technique. Author
- Couplers, Fasteners and Joints