High carbon ferrochrome powder is one of the chemical heat treatment methods for iron and steel. The steel works are heated in a chromized medium (such as chromic iron powder wetted with hydrochloric acid or a gas containing chromium chloride). The new active chromium penetrates into the surface of the steel and makes the surface resistant to corrosion and heat. Chromizing is the mold placed in the chromizing medium, at high temperature through the surface absorption and Cr, Fe, C mutual diffusion, in the mold surface to form a layer of Cr compound layer, namely chromizing layer. The chromizing layer can improve the surface corrosion resistance, anti - oxygen chromizing, anti - wear performance of the die. The surface of the die after chromizing is silver-gray, no pitting and no bonding, which can maintain the original finish and surface quality. Some molds after chromizing can significantly improve the mold life, such as Shanghai radio six factory 9CrWMn steel shell die, the original life is 100 or 1000 times, will produce the hair wear phenomenon, after chromizing treatment, the service life extended to 100,000 times. Powder chromizing is the mold buried in the chromizing agent, heating to 1050~1100℃, heat preservation for 5~10 hours, and then with the furnace to 600℃, air cooling. Powder chromizing agent is generally prepared by themselves, the current commonly used formula is :50% chromium powder, 2% ammonium chloride, 48% alumina, after 1100℃ melting. Chromized tanks are made of stainless steel or heat resistant steel. Mold after packing, to cover the inner lid, after 300 ℃, bake for 40 ~ 60 minutes make NH4Cl part decomposition, eliminate the residual air tank, then immediately with water glass lid, refractory clay sculptures, and under 80 ℃ drying, inner and outer layers fill, with cast iron to reduce and prevent the oxidation of the infiltration agent and sample, then to refractory clay sculptures good outer box cover. When the powder chromizing agent is used again, 20%NH4Cl and 5~15% new agent should be added. The thickness of chromizing layer is 0.02~0.04 mm, and the surface hardness is HV1300~1500.