N DT Abstracts pool preventing metal oxidation. Due to this situation, it is impossible to observe the pool by optical means. X-ray penetrating radiation can be effectively used for pool observation, weld path tracking, and observation of volume defects.
Lindegaard-Andersen, A.; Vedel, T.; Jeppesen, L.; Gottlieb, B. Film-based X-ray tomography combined with digital image processing: investigation of an ancient pattern-welded sword 39910
NDT International, Vol. 21, No. 6, pp. 407-410 (Dec. 1988) Film-based X-ray tomography and digital image processing have been used to investigate an inhomogeneous object of non-circular cross-section. The feasibility of using digital image processing to compensate for the poor contrast resolution inherent in film-based tomography has been demonstrated.
Working Group of Commission V of the International Institute of Welding (IIW) X-ray real-time imaging (radioscopy) for weld inspection: IIW 4th progress report 39742
British Journal of Nondestructive Testing, Vol. 30, No. 6, pp. 400-402 (Nov. 1988) Automated image interpretation in X-ray real-time inspection of welds is a complex field of pattern recognition. Reai-time conditions and system characteristics require a powerful hardware configuration and special image analysis algorithms, but because of intensive investigations in the last few years, the automated image interpretation can now be regarded as a practical alternative to visual interpretation of the display screen image. Powerful image processing systems for this application are now marketed by several manufacturers.
Garcia, C.; Emparan, A.; Garcia-Yague, M. Aspects to be solved in gamma rays evaluation of hollow cylinders. Case of cast valve weld ends: solutions derived by computer 39619
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 2060-2067. Pergamon Press, 3173 pp. (1988) Quality control specialists are faced with several alternatives when projecting the radiographic examination of hollow cylindrical forms in terms of piece dimensions. The first one of these alternatives is choosing the kind of radiation source to be used. This article only considers gamma ray isotopic sources, analyses the different problems that must be overcome in order to make, in each case, a correct choice of the exposure parameters (isotope and source size, film type and its format, source-fihn distance, penetrameter, etc.). As an example, examination of body weld ends of cast valves is described where both adverse geometrical and high radiographic quality requirements are often found. Finally, experiments carried out by the authors are described on systematization of methods for deriving the referred parameters with computer help.
Roye, W. X-ray testing of thermoplastic welding joints 39618
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 2051-2059. Pergamon Press, 3173 pp. (1988) It is well known that X-ray testing of plastics and their welds is problematic. The difficulties are discussed briefly and two ways which lead to improvements are demonstrated: the high current constant potential X-ray system and the newly developed Compton-backscatter technique.
Yeh, C.Y.; Huang, C.F.; Shyu, H.F. The mottling on radiographs for thin Inconel Alloy 718 welds 39615
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 2025-2034. Pergamon Press, 3173 pp. (1988) Some mottling has been observed on the radiographs for thin lnconel Alloy 718 welds and their appearance is very easy to confuse with that of true weld flaws, such as lack of fusion, crack, slag inclusion, etc. After careful investigation of these images, they were found to be caused mainly by diffraction from the structure of oriented coarse grains and partly by the difference in radiation absorption when X-rays penetrated through the segregation of elements. Experiments were carried out and the results supported the above theory quite well.
39609 Allen, A.J.; Hutchings, M.T.; Rainey, V.S. Measurement of through-thickness residual stress in T-butt weldments of offshore steel by high resolution neutron diffraction Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 1808-1817. Pergamon Press, 3173 pp. (1988) The use of high resolution neutron diffraction to measure, nondestructively, the residual strain and hence the residual stress variation through the heat affected zone and into the plate beneath the toe of a T-butt is described. The effects of the strain variation of post weld heat treatment, and of fatigue loading until a crack is formed in the plate, have been investigated. The results indicate the power of the neutron diffraction technique to obtain unique information on the strain distribution with a weldment. 39608 Arrondeau, P.Y.; Charbonnier, A. Robot for real time radiographic inspection of circumferential welds with computer processing of the whole system Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 1575-1579. Pergamon Press, 3173 pp. (1988) This system is the result of two pieces of research work conducted jointly by Institut de Soudure and Intersub. The first is aimed at implementing and optimizing real time radiography in the field of welded constructions and developing a computerized system for real time inspection. The second is aimed at implementing this inspection procedure by robotizing the system. This research work led to the development of a robot for the non-destructive testing of underwater pipelines. 39601 Rokhlin, S.I.; Guu, A.C. In-process radiographic monitoring of arc weld penetration Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 209-217. Nondestructive Testing Information Analysis Center, Texas, USA. In this study real-time radiography is used for in-process weld quality evaluation, with on-line testing of defect formation in the weld and welding process control. In this system, welding current can be remotely controlled during observation and computer processing of weld images. The experimental results are demonstrated for the submerged arc welding process. The welding pool is covered by a thick layer of the welding flux and, therefore, the pool is optically invisible. By using computer data of the gray levels of weld images and their histogram distributions, the three-dimensional shape of the submerged arc pool was studied. The depth of the welding pool can be measured in real time and can be used for weld tracking and process control.
Eyerkuss,R.F.; Engelbart, R.W. Automated radiographic inspection for circumferential welds 39600
Proceedings of the 16th Symposium on Nondestructive Evaluation, San Antonio, Texas (United States), 21-23 Apr. 1987. pp. 203-208. Nondestructive Testing Information Analysis Center, Texas, USA. Static radiography of complex welded aerospace components is costly in both time and materials. In an effort to reduce these costs and increase productivity, McDonnell Douglas Astronautics Company has developed a prototype automated radiography system for the inspection of circumferential welds. Following initial set-up of the hardware, and through the assistance of user friendly software, the operator selects a technique which is pre-programmed and identified by part number. The exposure parameters, part manipulation, and film advancement are then automatically controlled throughout the inspection. Accuracy and repeatability of part motion can be maintained within a fraction of a degree. All views of the weld appear on a single strip of five-inch wide roll film, eliminating the need for loading and unloading of cassettes. Preliminary trials indicate that with reduction of operator involvement, elimination of film cassette loading, and decreased processing time, an average manhour savings per part of 55 percent can be realized, depending upon size and geometry.
Anon. X-ray real-time imaging (XRTI) for weld inspection. 3rd Progress report 39287
Welding in the World, Vol. 26, No. 5-6, pp. 100-107 (1988) A third progress report is presented on the use of X-ray real-time imaging (XRTI) for weld inspection. It focuses on the attainable performance of XRTI systems. In industry large financial savings have already been made by using this technique. Although in its early stages, the use of pattern recognition methods may lead to automaticrecognition of weld defects by computer in the future.