Current Niobium Developments in High-Carbon Steel Applications

摘要

The application of niobium (Nb) in high carbon steels enhances both the metallurgical properties and processability products such as steel bar, sheet and plate. Such process and product metallurgical improvements relate to the Nb-pinning effect of the austenite grain boundaries in microalloyed 0.25 to 0.95%C steels during the reheat furnace process prior to rolling. Consequently, Nb microalloyed high carbon automotive and long product steel applications have been developed. The Micro-Niobium Alloy Approach0 is described and correlated to a variety of high carbon steel grades and applications. Metallurgical Operational Implementation (MOI) links the product requirements to the mill capability and resultant process metallurgical implementation. This integrative approach connects the Nb process and physical metallurgy necessary to achieve the desired ultra-fine grain, homogeneous high carbon steel microstructures that exhibit superior toughness, strength, fatigue performance and weldability.