Metallurgical aspects of induction-bending thick-walled super duplex pipework

Abstract

In this article, the authors' present findings indicate that the induction-bending process can have a severe detrimental effect on the mechanical properties and the corrosion resistance of super duplex stainless steel. After outlining the parametric testing of the pipe that produced reduction in properties, the article presents comparative data from mechanical testing, corrosion analysis, and micrographic analysis before and after induction bending and after post-bend heat treatment. An explanation for the deterioration of properties is provided in terms of metallurgical characteristics; the root cause of deterioration is discussed; a method of restoring the mechanical and corrosion resistant properties is provided; and finally, process improvements are suggested which might, if adopted, prevent the re-occurrence of this phenomenon in the future.