Iron
niobium is mainly used in the smelting of high temperature (heat resisting) alloys, stainless steels and high strength low alloy steels.
Niobium In stainless steel and heat resistant steels, stable niobium carbide is formed with the carbon in the steel.
It is uniformly distributed in the grain boundary of steel to prevent the grain growth of steel under high temperature, and play a role in refining the structure of steel, which can improve the strength, toughness and creep properties of steel.
The chemical affinity of niobium and carbon is much greater than that of chromium and carbon. Therefore, the presence of niobium in stainless steel can prevent the precipitation of chromium carbide at the grain boundary of the steel, thus improving the corrosion resistance of the steel.
The niobium and nitrogen in steel produce stable niobium nitride, which improves the corrosion resistance of steel surface.
The niobium and oxygen in the steel form stable niobium oxide, which makes the surface of the steel form niobium oxide film, which can prevent the diffusion of oxygen to the inside and play an anti-oxidation role.
The addition of Nb0.015% ~ 0.05% in carbon steel can refine the structure and make the steel have good formability and weldability.
Nb has a strong effect on the austenite recrystallization of steel, so that the steel can effectively control the rolling at higher temperature, and the effect of strengthening and toughening is very remarkable.
Therefore, the amount of niobium as a microalloying element in carbon steel is greatly increased.
The use of niobium in microalloys in the United States, which accounted for only 1.9 percent of total niobium consumption in 1959, rose to 68 percent in 1988.
Niobium plays an important role in solution strengthening and carbide precipitation strengthening in the superalloy, which improves the yield strength and surface stability of the superalloy.
The weight of niobium is one of the lighter refractory metals, and it is also one of the factors for the extensive use of superalloys.
Niobium - nickel alloy as the additive of nickel - base superalloy is mainly used to produce 718 alloy.
The coercivity of permanent magnet alloy can be improved by adding niobium.
The addition of niobium in cast iron is helpful to the formation of spheroidization and pearlite structure.
It can inoculate and refine the structure of casting.
Niobium can improve the strength, toughness, hardness and service life of castings at high temperature.
The welding rod uses iron niobium as solder component to improve the welding quality.
