The production and application of modern high strength niobium microalloyed structural steels

Abstract

Niobium (Nb) is widely applied as a key micro-alloy in the production of modern high strength structural steels and in particular allows a combination of thermal and mechanical treatment during plate production via the TMCP route. A consequential metallurgical benefit is the development of very fine microstructures resulting in high strengths as well as high toughness in spite of a lean steel chemical composition. Apart from the standard mechanical properties, such steels have to meet increasing performance requirements taking into consideration on-site weldability, cold temperature performance and other environmental conditions such as seismic zones. This paper presents and discusses some of the recently developed niobium bearing high strength structural steels that have been employed in recent projects, which have offered substantial savings in terms of material fabrication costs for a wide range of applications such as bridges and buildings.