Basic metallurgy of modern niobium steels

It is well known that niobium is added to a wide range of steels for improving processing, microstructure, properties and performance. Over the last two decades, the use of Nb has also permitted new steels with attractive properties to be developed. Furthermore, the addition of Nb to existing steels such as ferritic stainless and IF steels has also led to improvement. The goal of this paper is to review the basic behavior of niobium in a wide range of steels, including both the traditional steels and also some of the newer versions. Particular emphasis has been placed on the basic metallurgical principles that apply to these steels, for it is the application of these principles that allows the composition - processing - microstructure - mechanical property relationships to be rationalized and exploited. The application of basic metallurgical principles has resulted in a predictive capability that has led to alterations in composition and processing for the purpose of producing steels with superior mechanical properties and improved overall performance. (AU)