The role of titanium and niobium in stainless steel
The affinity of titanium and carbon is the largest among all alloying elements except niobium. Even when the content is small, it can significantly reduce the carbon content of austenite, and preferentially form titanium carbide with carbon, avoiding the formation of chromium-depleted areas. , Prevents intergranular corrosion.
The steel with Ti content of 1% and C content of 0.2% is martensitic after high temperature quenching, and is not easy to soften during tempering, but the secondary hardening effect is weaker than that of molybdenum steel and tungsten steel.
(2) The role of niobium
The affinity of niobium and carbon is the largest among all alloying elements, so it can preferentially form niobium carbide with carbon, avoiding the formation of chromium-depleted areas and preventing the intergranular corrosion of stainless steel. Niobium can also increase the high temperature creep rupture strength of steel.