Among all kinds of microalloyed elements in steel, waste niobium is the most effective microalloyed element. The role of niobium is so great that there are abundant niobium atoms in iron atoms, which can improve the properties of steel. In fact, adding 0.001% to 0.1% niobium to the steel is enough to change the mechanical properties of the steel. For example, when 0.1% alloying element is added, the yield strength of steel is increased as follows: niobium 118MPa; Vanadium 71.5 MPa; Molybdenum 40 mpa; Manganese 17.6 MPa; Titanium is zero. In fact, the yield strength of steel can be increased by more than 30% by adding 0.03%-0.05% Nb. The cost of steel has risen by just $1 a tonne. For example, the yield strength of ordinary medium carbon steel is generally 250MPa, and the strength can be increased to 350-800mpa by adding trace niobium.
Niobium, as a microalloyed element, does not change the structure of iron when it is added to steel. The strengthening effect of niobium on steel is mainly fine grain strengthening and dispersion strengthening. Niobium energy and carbon nitrogen in steel produce stable carbides and carbonitrides. The carbide can also be dispersed to form steel with fine crystallization.
Niobium can also induce precipitation and control cooling rate to realize dispersion distribution of precipitates. Adjust the toughness level of the steel over a wide range. Therefore, adding niobium can not only improve the strength of steel, but also improve the toughness, oxidation resistance and corrosion resistance of steel! Reduce the transition temperature of steel brittleness, obtain good welding and forming properties.
