chapa de aço revestida de uma camada metálica à base de zinco e processo de obtenção dessa chapa.

摘要

The invention concerns a steel plate coated with a metal layer based on zinc and a zinc hydroxysulphate layer, whereof the surface density of sulphur is more than 0.5 mg/m2. The invention also concerns a method for obtaining said plate by treating a zinc coated sheet metal: either in a highly alkaline sulphate solution under polarization; or in a sulphate solution containing Zn2+ ions without polarization. The hydroxysulphate deposit brings about a pre-lubricating effect applicable to operations for forming sheet metal.