EVALUATION OF DEFECTS TYPE "GOUGE" IN 304L STAINLESS STEEL PIPES USED IN THE MANUFACTURE OF SURGICAL NEEDLES

Abstract

The production of cannulae, materials that are used in the manufacture of medical devices are made from a 304L stainless steel strip rolled in a pipe and then welded by GTAW process. After this procedure, the tube undergoes in a series of drawing passes with and without annealing to reduce its diameter. Finally, the steps are carried cut, and pointing and cleaning material. In the drawing, a series of defects called "gouge" is found, causing high losses in the process, depending on the technical specifications discontinuities. Initially, in order to characterize and detect possible causes of defects analyzed the characteristics of the process, from welding to drawing without annealing. Then, analyzes were performed with scanning electron microscopy, to evaluate some metallurgical characteristics of the material. As the goal was to characterize the defect, several possible causes emerged as the influence of current or welding speed, temperature treatment along with the reactions of ammonia gas in the generation of discontinuities, the speed of drawing or the amount of lubricating oil. It was concluded that the welding process is not the cause of the fault as well as drawing without annealing. The possibility of the cause of the discontinuity was annealed drawing process. Thus, various proposals have emerged for future work.