Ferrite is a interstitial solid solution of carbon dissolved in & alpha; - Fe, which is usually represented by the symbol F. It has a body centered cubic lattice, and its carbon solubility is very low, only 0.0008% of carbon can be dissolved at room temperature, and the maximum carbon solubility is 0.02% at 727 ℃. Ferrite is one of the most common structural forms in steel, which can be generally divided into six categories: grain boundary ferrite, widmansferrite side piece, widmansferrite serration, intragranular ferrite, intragranular widmansferrite and massive ferrite. Ferrite is a product of transformation from high temperature austenite. According to its morphology, it can also be divided into reticular ferrite, massive ferrite, dispersed point ferrite and acicular ferrite.