High strength steel for steel constructions

Abstract

The field of application for high strength steel reaches from offshore and hydropower constructions to ship- and bridgebuilding. Steels with very high strength (up to 1,100 MPa) are generally produced by a quenching and tempering process (Q+T). Extremely high strength is always associated with higher amounts of alloying elements and tends to result in higher hardenability which leads to a higher risk for brittle fracture and hydrogen induced cracking in welded constructions. In particular this is the case when the optimal processing parameters for welding are not used. Re- garding the overall efficiency in steel constructions, the choice of a steel with moder- ate strength but excellent weldability can be an advantage. These properties can be achieved in a plate by using the thermomechanically controlled process (TMCP). The good weldability of this material allows the choice of efficient and cost-saving welding processes. This article describes the state of the art in production of high strength steels, especially an overview on the different delivery conditions is given. The proc- essing properties of a thermomechanically rolled steel of 500 MPa minimum yield strength are presented in comparison with steels of other delivery conditions.