The effects of niobium (Nb) and vanadium (V) additions on the properties of plain carbon (C) steel have been well known for some years now. Recently, through refinements in processing technology, very effective use has been made of relatively small amounts of Nb or V (up to 0.2 wt-%) to significantly increase yield strength and improve notch toughness.These improvements have resulted through optimization of Nb and V carbonitride precipitation hardening, ferrite grain size refinement, and a reduction in C content.The latter item also significantly improves weldability.Nearly all of the industrialized countries of the world have taken advantage of the economy of producing higher strength steels with a minimum of extra alloying cost.This is especially true for structural applications where weight savings is so important.The United States is certainly one of the leaders in this area and one only has to look at a recent American Society for Metals (ASM) survey of high-strength low-alloy (HSLA) structural steels to see the wide variety of Nb- and V-containing steels available.