SURFACE HARDENING METHOD FOR LARGE MOLDING STEEL

摘要

A surface hardening method for a large mold is provided to improve abrasion resistance and corrosion resistance of the product, and extend life time of the mold by heating and cooling a surface of the mold and treating the mold by oxide-nitride. A surface hardening method for a large mold comprises the steps of: heating and cooling a surface of the large mold; and treating the large mold by oxide-nitride in a plasma furnace. The surface of the large mold is plasma-oxidized for 1 hour in a condition that temperature in the furnace is 450 to 550°C and Ar and O2 are supplied by a ratio of 2:8 or 8:2. The surface hardening method uses one of the flame hardening step, the high frequency hardening step, and the laser hardening step.