High temperature in-situ X-ray analysis of a lean duplex stainless steel

Abstract

Duplex Steels have been used for different applications in the oil and gas industry due to their high strength and corrosion resistance. In this work, a Lean Duplex Steel (UNS S32304) has been investigated by High Temperature In-Situ X-Ray Diffraction, in order to address phases transformations occurring during high-temperature real time exposure and the formation of deleterious phases such as sigma phase. Samples were subjected to a temperature of 800 °C for different time intervals (30 and 60 min) inside a high temperature furnace attached to an x-ray diffractometer. Formation of sigma phase was observed, both in the ferrite grain boundaries and in the ferrite/austenite interface. The volume of sigma phase was measured by quantitative phase analysis using the Rietveld method and results varied from 2.80 to 15.92% in volume.