| 摘要 |
PURPOSE:To produce a cold rolled steel sheet excellent in chemical conversion treating property independently of the type of steel by adding fine grains of metal oxide with a specific grain size to a rust preventive oil to be applied to a cold rolled steel sheet and fixing the fine grains on the surface. CONSTITUTION:As pretreatment for a coating stage for automobiles, etc., the fine grains of metal oxide of <=1mum grain size, to be nuclei of conversion treated crystals, are added to a rust preventive oil by 1000-5000g/m<3> and this rust preventive oil is electrostatically applied to the surface of the steel sheet, by which the metal oxide is allowed to adhere uniformly to the steel sheet surface. As a result, rusting at the steel sheet surface is prevented by the action of the rust preventive oil, and the fine grains of metal oxide are fixed on the steel sheet surface in one or two weeks. Accordingly, the fine grains become the nuclei of the conversion treated crystals, and the dense and uniform conversion treated crystals can be obtained. |
