Stir-fried steel in Han dynasty: it was named after constantly stirring in the smelting process as if it were cooking. The raw material for frying steel is pig iron. The key point of operation is to heat pig iron to liquid or semi-liquid, and reduce the carbon content to the composition range of steel and wrought iron by blowing or spraying concentrate powder silicon oxide, manganese and carbon. The products of fried steel are mostly low carbon steel and wrought iron, but if controlled well, medium carbon steel and high carbon steel can also be obtained.