PURPOSE:To obtain an artificially rusted weather resistant steel sheet having more effectively improved corrosion resistance of the rust film by treating a steel sheet with a rusting soln. consisting of pure water, sulfuric acid, nitric acid, an aq. ammonia soln. and Fe2(SO4)3. CONSTITUTION:A steel sheet is treated with a rusting soln. consisting of pure water, sulfuric acid, nitric acid, an aq. ammonia soln. and Fe2(SO4)3.2H2O or further contg. at least one of CuSO4.5H2O and (NH4)2HPO4 as additives to obtain an artificially rusted weather resistant steel sheet. This weather resistant steel sheet is further treated with a sodium silicate soln. as required. The corrosion of the base iron is effectively inhibited, cracks caused in the steel sheet are coated and the weather resistance can be improved.
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