Influence of the Plate Thickness on Fracture and Impact Toughness of Duplex Stainless Steels

In the last two decades, the use of duplex stainless steel (DSS) has increased significantly in structural applications due to their low maintenance costs, excellent corrosion resistance in highly corrosive environments, and high mechanical strength. The production of thicker plates by hot rolling leads to larger grains sizes in the material. Besides this, different plate thicknesses have different cooling rates after hot rolling which influence the intermetallic formation of the material. Both these parameters have an influence on the impact and fracture toughness of steel materials. Nevertheless, for duplex stainless steels, a concept for the choice of steel material to avoid brittle fracture according to EN 1993‐1‐10 does not exist so far. For this reason, an investigation has been started in the frame of the German FOSTA research project (P 1390). Two types of DSS plates, 1.4462 and 1.4162, with varying thicknesses were selected and tests were conducted on base and welded material in order to investigate the influence of the plate thickness on the impact and fracture toughness of the material. Furthermore, the suitability of the Master Curve concept and transition temperature correlation for duplex stainless steels has been examined.