Vanadium carbide in the metallurgical industry, chemical industry, atomic energy industry, aerospace industry, agriculture, medicine and other fields has a very wide range of applications. The addition of vanadium carbide in steel can increase the strength of steel, improve the toughness and plasticity of steel, and improve the process performance of steel, but most of the vanadium carbide produced at present is used in metallurgical industry, as an important microalloying element and alloying element in steel to improve the performance of steel. To improve the service performance of vanadium steel products, then, let's understand the alloying effect and application of vanadium carbide in steel!

01, the behavior and main role of vanadium carbide in steel

The position of vanadium carbide in the periodic table of chemical elements determines its chemical properties. It is a strong carbide and nitride forming element. Vanadium has a body-centered cubic structure. Vanadium carbide is located in the 4th period and VB group on the periodic table of chemical elements. The electron number of its 3d layer is 3. The solid solution and precipitated vanadium will affect the development of the organization and can be solid-dissolved in steel at any temperature. Steel contains a certain amount of carbon and nitrogen, combined with vanadium in the form of carbide, nitride or carbonitride precipitation in steel, these organizational characteristics will affect the various properties of steel.

When the nitrogen content is low, the solubility product of vanadium carbonitride in austenite is much higher than that of niobium carbide. Therefore, the main function of vanadium carbide is interphase precipitation and precipitation strengthening in ferrite during phase transformation. Vanadium carbonitride can be completely dissolved in austenite under 900, and the solid solubility of vanadium in austenite is larger than that in ferrite.

The main role of vanadium carbide in steel is as follows.

1) Refine the structure and grains of steel, increase the grain coarsening temperature, reduce the overheating sensitivity, and improve the strength and toughness of steel.

2) When austenite is dissolved at high temperature, the hardenability of steel increases; on the contrary, if carbides are present, the hardenability of steel will decrease.

3) Improve the hardenability and tempering stability of quenched steel, refine the grain, and produce secondary hardening effect.

4) The solid solubility product of vanadium carbide and vanadium nitride in austenite is higher. Therefore, cracking due to precipitation is less likely to occur at a high temperature, and the tendency of cracking of the billet during solidification is small.

5) vanadium carbonitride precipitation temperature is low, uniform microstructure along the steel section. In a wide temperature range can be obtained uniform recrystallization grains, solid solution in austenite, grain boundary migration traction is low. This is conducive to the recrystallization of austenite, easy to implement recrystallization control rolling, finishing temperature has little effect on mechanical properties. Compared with other microalloyed and alloyed steels, vanadium-containing steels have small rolling resistance and are comparable to carbon-manganese steels.

6) Precipitates in ferrite or martensite, promotes the precipitation of vanadium by increasing the nitrogen content in the steel, and achieves a greater precipitation strengthening effect. Precipitation strengthening effect is produced. Generally, the precipitation strengthening increment in ferrite is 50MPa ~ 100MPa, which is a good technology in the production of high-strength hot-rolled ribbed steel bars to save the amount of vanadium and increase the amount of precipitation strengthening.

7) The combination of vanadium and nitrogen is strong, which can form vanadium nitride, which is beneficial to reduce the strain aging of steel. Steel bars that have undergone cold deformation are important in service.

8) The addition of vanadium to the martensitic steel can enhance the anti-tempering softening performance of the steel, or precipitate vanadium carbide during the tempering process, resulting in a secondary hardening effect, so that the steel maintains the shape of the martensitic lath during the tempering process.

02. Application of Vanadium in Iron and Steel Industry

On the one hand, the addition of vanadium in steel plays the role of deoxidation and denitrification, on the other hand, it can also improve the performance of steel, so as to reduce the production cost and reduce the amount of steel. Vanadium steel has the characteristics of high strength, toughness, wear resistance and good corrosion resistance. At present, most vanadium is used as an additive component of steel to produce high-strength low-alloy steel, high-speed steel, tool steel, stainless steel, spring steel, bearing steel, etc. It is widely used in machinery manufacturing, automobiles, aviation, railway transportation, bridges and other industries.

Application of Vanadium Carbide in High Strength Low Alloy Steel

Most vanadium carbides are used in the production of high-strength low-alloy steels. Improve the welding performance of steel, is the ideal alloying element of ordinary low alloy steel, ordinary low alloy steel to add vanadium carbide can improve the strength after normalizing, yield ratio and low temperature toughness, low temperature structural steel can also be applied vanadium alloying technology to improve the strength and toughness of steel.

Application of Vanadium Carbide in Alloy Die Steel

One of the main application areas of vanadium carbide as an alloying element is in alloy steels. Vanadium carbide in tungsten-containing high-speed tool steel to prevent grain growth, vanadium carbide in alloy steel, not only refine the grain, reduce the sensitivity to overheating, but also increase the tempering stability, wear resistance, extend the life of the mold, improve the red hardness and cutting ability of the steel, increase the wear resistance, extend the role of high-speed tool life.