Application of the Master Curve concept on the choice of duplex stainless steel to avoid brittle fracture

Abstract

ABSTRACTDuplex stainless steel gets more and more common in structural applications even in steel bridges. For these cases, the choice of duplex stainless steel material to avoid brittle fracture is of great importance as e.g. steel bridges are exposed to low temperatures, generally down to −30 °C or even lower, and fatigue loads. EN 1993‐1‐4 also covers duplex stainless steel, but the given toughness requirements for duplex stainless steel are insufficient. Due to this fact, first investigations have been carried out on various duplex stainless steel base materials and welded specimens based on the fracture mechanic based concept of EN 1993‐1‐10 including the Wallin Master Curve concept. The objective was to achieve a first insight in the applicability of EN 1993‐1‐10 for structural applications with different types of duplex stainless steels in principle. In this frame, Charpy and fracture mechanics tests have been evaluated for 1.4462, 1.4362 and 1.4162 duplex stainless steels of 30 mm and 50 mm thick base materials and weldments. The results have been transformed into the general approach used in EN 1993‐1‐10 originally developed for ferritic structural steel considering the structural detail of a welded longitudinal attachment with a semi elliptical surface crack at the weld toe. The results demonstrate that the investigated duplex stainless steels and their weldments show a very good toughness behaviour and that the EN 1993‐1‐10 model can be transformed for application of duplex stainless steel. The paper presents these first results.