(1) refine the structure and grain of steel, increase the grain coarsening temperature, so as to reduce the overheating sensitivity, and improve the strength and toughness of steel.
(2) increase the hardenability of steel when it melts into austenite at high temperature; In contrast, the hardenability of steel is reduced in the presence of carbides.
(3) increase the hardenability and tempering stability of hardened steel, refine grain, and produce secondary hardening effect.
(4) the solid solubility product of vanadium carbide and vanadium nitride in austenite is high. Therefore, it is difficult to produce cracks caused by precipitation at high temperature, and the tendency of cracks in billet during solidification is small.
(5) the precipitation temperature of vanadium carbonitride is low, the solid solution is in austenite, and the drag force of grain boundary migration is low. This will be conducive to austenitic recrystallization, easy to implement recrystallization control rolling, along the steel section of uniform structure. Uniform recrystallized grains can be obtained in a wide range of temperatures, and the final rolling temperature has little effect on the mechanical properties. Compared with other microalloyed steels and alloyed steels, vanadium steel has less rolling resistance and is comparable with carbon manganese steel.
(6) precipitation in ferrite or martensite produces precipitation enhancement. Generally, precipitation enhancement increment in ferrite ranges from 50MPa to 100MPa. The precipitation of vanadium can be promoted by increasing the nitrogen content of steel and the precipitation strengthening effect can be obtained. This is a good technique in the production of high strength hot rolled ribbed steel bar, which can save the use amount of vanadium and improve the precipitation strengthening amount.
(7) the strong binding force of vanadium and nitrogen can form vanadium nitride, which is conducive to reducing the strain aging of steel, which is very important for the steel bar that has undergone cold deformation in the service process.
(8) adding vanadium to martensitic steel can increase the tempering softening property of steel, so that the steel can maintain the shape of martensitic slab during tempering, or the vanadium carbide can be precipitated during tempering, resulting in secondary hardening effect.
