Induction Bending Effects on Mechanical Properties and Corrosion Resistance of Duplex Stainless Steel UNS S31803 Pipes

Abstract

Duplex stainless steels are well known austenitic-ferritic alloys which combines good mechanical resistance and excellent corrosion resistance. Due to this fact, this steel family is widely employed in offshore piping applications. However, these alloys require great care in thermomechanical processing, such as welding, since they might present serious decrease in corrosion resistance and toughness at the welded joint when compared to the base metal. Undeniably, welding is one of the major processes employed in pipe and industrial equipment assembly, thus requiring higher expertise and caution in order to achieve the desirable good combination of properties of duplex stainless steel alloys. In this context, induction bending process comes as an efficient alternative to reduce the number of weld joints in piping designs. In this work, induction bent tubes were characterized after bending in temperatures inside and outside the standard recommended range, that is, between 950 and 1150°C. Microstructural characterization, mechanical testing and corrosion tests were performed, indicating that the properties of curved materials remained comparable to a solubilized state. Therefore, the electromagnetic induction bending process proves to be not only a viable tool in thermomechanical processing of these materials, but also more productive.