When the forgings are heated, the residence time is too long at high temperature, the oxygen in the furnace and the oxygen in the water vapor combine with the iron atoms of the forgings and the phenomenon of oxidation is called oxidation. Fusible formed by iron oxide adhesion on the surface of the metal solid oxide skin, such as forging prior to remove impurities, would be pressed into the surface of forgings, clean up or after pickling, partial peeling sag formed forging surface pitting, serious when forging geometry size, machining allowance, or a result of insufficient and make the parts with black face on scrap, is will have effect on the precision of the die forgings.

The methods to prevent oxidation are:
(1) reduce the stay time at high temperature when the forging is heated, carry out rapid heating, and try to use the operation method of less loading and frequent loading.
(2) keep a micro oxidation atmosphere in the furnace, reduce the water vapor content in the furnace, carry out less oxidation heating or to protect the coating treatment,
(3) keep a small positive pressure in the furnace to prevent cold air from inhaling into the furnace.
(4) after the die forging is heated, brush, high pressure water (the pressure is at least 10Mpa) punch or apply deformation (as long as there is 0.05% of structural steel? 0.2% of the degree of deformation) to remove the oxide scale.