| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
Segregation in Steels
|
| Presentation Title |
Influence of Boron Segregation on Sigma Phase Formation in Duplex Steels |
| Author(s) |
Roman Schuster, Andreas Keplinger, Laszlo Solyom, Anna Krejci, Nicolas Garcia Arango, Franz Kiraly, Aurelie Jacob, Emad Maawad, Erwin Povoden-Karadeniz |
| On-Site Speaker (Planned) |
Roman Schuster |
| Abstract Scope |
Duplex steels with a 1:1 molar ratio of austenite and ferrite combine excellent mechanical and corrosion resistance properties. However, due to high concentrations of alloying elements they are prone to the formation of deleterious phases at processing temperatures, most importantly sigma phase, which leads to a decrease in toughness and a worsening of the corrosion resistance. We found that in the early stage of precipitation during isothermal holding after cooling from a solutionizing treatment sigma phase forms at ferrite-ferrite and more commonly ferrite-austenite boundaries. In particular, sigma phase forms preferentially where narrow ferrite regions are enclosed by austenite. We found that the growth of austenite into ferrite during and immediately after cooling from solutionizing leads to an increase of sigma phase promoting elements Mo and Cr in these regions. The addition of boron reduces these chemical heterogeneities by lowering the boundary energies, thereby impeding the formation of sigma phase. |