**8. Chromium steels**

Chromium is less expensive than Ni. Chromium is a carbide former and forms (Cr7C3, Cr4C) or complex carbide [(FeCr)3C]. This carbide has high hardness and wear resistance. It has 13% solubility in austenite and unlimited solubility in ferrite. In alloying steels, chromium containing more than 5% improves the corrosion resistance and high temperature properties.
