Influência da geometria, comprimento de queima e modo de aplicação da força no reparo por atrito com furo passante em aço inoxidável duplex

Abstract

The repair of structures using electric arc welding for the oil industry presents safety risks to the operator and a considerable number of defects inherent to the process. A new technique more suitable to the operating conditions of this field needed to be developed then, and the friction welding perfectly fits such application. The objective of this study was to better understand this process when using through holes on the base material. The study was also limited in terms of the material to be used, which was the duplex stainless steel UNS S32205, another requirement from the oil industry. Several tests were performed to help understand how each of the parameters analyzed interfere on the welding quality. Three different geometries were initially proposed, with different taper angles for the consumable rods on each one of them. The burn-off length and number of stages used to apply the force also differed from on test to the other. Once the testings were finalized the welding joints went through a preparation process so that macro and micrographs could be obtained and the welding quality could be evaluated. Lastly, a microhardness profile was obtained for the joints that presented the most satisfying results. Throughout this work it was observed that the geometry that presented the best results was the one with a taper angle of 26° for the rod and 30° for the hole on the base material. The use of this geometry along with higher values for the burn-off length and the two-stage pressure process led to higher processing times, which resulted in better quality welding joints, with no apparent defects or unfilled areas.