Determination of Susceptibility to Intergranular Corrosion of UNS 31803 Type Duplex Stainless Steel by Electrochemical Reactivation Method: A Comparative Study

Mehmet Emin Arıkan,Rafet Arıkan,Mustafa Doruk

doi:10.1155/2012/478508

Abstract

In the present study as in our previous studies (Arikan and Doruk, 2008 and Arikan et al., 2012), similar specimens taken from a hot rolled cylindrical duplex stainless steel (DSS) bar with 22% Cr grade were solution annealed at 1050°C and then aged at 800∘C from 100 to 31622 min for sensitization treatment. Double loop electrochemical potentiodynamic reactivation and standard weight loss immersion acid tests were conducted. The solution annealed samples were found unsensitized. The samples aged for 100 min were less sensitized whereas samples aged for 316 min and more time were sensitized. The degree of sensitization (DOS) can be attributed to higher contribution of chromium and molybdenum depleted areas that result from intermetallic phases. However, especially the samples aged from 3162 to 31622 min have revealed chromium replenishment. Consequently, the degree of sensitization was lowered in comparison to the results obtained in previous studies.

Highlights

Duplex stainless steels (DSS) are Fe-Cr-Ni alloys having an approximately volumetric fraction of 50% ferrite and 50% austenite in their microstructures
The results indicate that the σ phase was partitioned in Cr and
The curve obtained from the solution annealed sample is treated as a reference and compared with the others

Summary

Introduction

Duplex stainless steels (DSS) are Fe-Cr-Ni alloys having an approximately volumetric fraction of 50% ferrite and 50% austenite in their microstructures Their main feature is that they compromise favorable corrosion resistance of austenitic stainless steels with good mechanical properties [1,2,3,4]. One of the possible phases to be formed is the sigma phase (σ), a hard and brittle intermetallic compound, rich in Cr and Mo, which is formed from ferrite [6]. This phase has deleterious effect upon both mechanical and the corrosion properties [7]

Objectives

Methods

Results

Conclusion