Vanadium grain refinement mechanism
Vanadium prevents the growth of large grains during cooling by forming fine carbides and nitrides. This increases the toughness of the steel.
Physical-Chemical Mechanism of Action
Vanadium reacts with carbon and nitrogen in the molten phase to form fine carbides (VC) and nitrides (VN). These fine compounds block the growth of large grains in the austenitic structure.
Metallurgical Relevance & Welding Risks
A sufficient vanadium content prevents the formation of glass-hard martensite and reduces susceptibility to hot cracking. Too little vanadium, however, can lead to coarse grain formation, which impairs the toughness and formability of the steel.
Workshop Practice & Instructions
To make the most of the vanadium grain-refining mechanism, the vanadium content in the melt should be kept between 0.1% and 0.4%. Cooling steps should be controlled to ensure uniform deformation and grain formation.