A comparative study into the fracture toughness properties of duplex stainless steels

Beside their high mechanical strength, duplex stainless steels are a suitable choice in highly corrosive environments. These types of steels are used in steel bridges more and more frequently exposed to low temperatures and fatigue loads. However, for low temperature applications, it must be guaranteed that brittle fracture is avoided since duplex stainless steel shows a toughness-temperature relationship similar to that of carbon steel. For this reason, in the frame of the German national FOSTA research project P 1390, comprehensive investigations have been started into the material selection of duplex stainless steel to avoid brittle fracture considering the fracture mechanic based background of EN 1993-1-10. For this purpose, Charpy-V impact tests and fracture toughness tests have been systematically carried out for various duplex stainless steels in order to create the basis for the development of toughness requirements for new duplex classes. The validity of the already existing Master Curve concept and the applicability of the transition temperature correlation for duplex stainless steels based on experimental fracture toughness and Charpy-V impact tests have been investigated. The aim of this contribution is to present first results of these investigations.

Automated summary

In addition to their high mechanical strength, duplex stainless steels are increasingly being used in highly corrosive environments, particularly in steel bridges exposed to low temperatures and fatigue loads. However, measures need to be taken to prevent brittle fracture in low temperature applications. A comprehensive study has been conducted to select duplex stainless steel materials and avoid brittle fracture, based on the fracture mechanics principles of EN 1993-1-10. Charpy-V impact tests and fracture toughness tests were carried out on various duplex stainless steels to develop toughness requirements for new duplex classes. The validity of the existing Master Curve concept and the applicability of the transition temperature correlation for duplex stainless steels were investigated through experimental tests. This contribution presents preliminary results of these investigations.