Weatherproof steels generally adopt refining-smelting (converter, electric furnace-microalloying treatment-argon blowing-LF refining-low superheat continuous casting (feeding rare earth wire) - controlled rolling and cooling process. During smelting, scrap steel is added into the furnace together with burden, and is smelted according to conventional process. After tapping, deoxidizer and alloy are added. After argon blowing treatment, molten steel is casted immediately. After argon blowing, the molten steel is casted into slab by continuous caster. Due to the addition of rare earth elements in the steel, the weathering steel is purified and the inclusion content is greatly reduced.