PRODUCTION OF ALLOY MATERIAL EXCELLENT IN ZINC PHOSPHATE PROCESSABILITY AND FORMABILITY

摘要

PURPOSE: To obtain a magnesium-contg. aluminum alloy material excellent in zinc phosphate processability and formability by treating the oxide film layer or surface layer so that a specified mass of the oxide film is dissolved off. ;CONSTITUTION: An Al alloy material contg. ≥0.4 mass% Mg and with the oxide film consisting essentially of MgO formed on its surface is treated to dissolve off the surface layer directly below the oxide film. In this case, the material is treated in an inorg. acid or in an acidic soln. consisting essentially of the inorg. acid, and the mass of the formed oxide film is measured. The oxide film layer or surface layer is treated based on the dissolution rate of the oxide film in the acidic soln. in the previously obtained respective treating conditions so that a specified mass of the oxide film is dissolved off. The treatment is carried out under conditions where the oxide film or Al alloy material having a mass of 0.8 to 1.5 times that of the oxide film is dissolved off. Consequently, a material appropriate as the Al alloy sheet for an automobile with press forming and zinc phosphate processing as the process before coating is provided.;COPYRIGHT: (C)1996,JPO