This alloying element is not usually observed in large percentages and is more often found in the super-alloy, special high-speed steels groups.
It will increase both the hot hardness and the hot impact toughness. There is a slight tendency to reduce the steel's hardenability (this does not mean resulting final hardness). It can also produce some resistance to the reduction of the hardness of martensite on the tempering procedure, but it is not significant.
It will improve a high-speed steel's hot-cutting ability, which means that the frictional temperatures generated from high-speed machining will not reduce the steel's surface hardness. Because it will reduce the hardenability, it will be necessary to increase the carbon content. It is usually found in steels such as T15 and M33.
Footnote to the addition of Vanadium
It should be both noted and considered that when tempering in the range of 930-1110°F (500-600℃) with tool steels that contain carbide-forming elements (like those mentioned in this series with vanadium), tempering will cause the primary formation of finely dispersed, alloy-rich carbides and will assist in the secondary-hardening effects.
It is necessary to exercise great care in temperature control and observation of the recommended hardening (austenitizing) temperature because overheating will dissolve any excess carbides.