Historical perspective on the use of niobium microalloying in structural steels

The first commercial trials of steels with niobium as a microalloy addition occurred in the USA in the late 1950s and were a response to a reduction in the price of niobium following the Korean War together with the discovery of huge reserves of niobium ore in Brazil and Canada. For the first few years, the production of such steels was restricted to the hot strip mill route, but when the mechanism of the effect of niobium on steel was better understood other steel production routes became available. It was soon observed that the properties of structural steels in particular, were significantly improved including strength, toughness and weldability. The first national standard for niobium-treated steels appeared in the UK in 1962. The existence of this standard, together with a better knowledge of the role of niobium in steel, encouraged a world-wide interest and led to a rapidly growing market for niobium-microalloyed structural steels. (AU)