Abstract: The surface of an aluminum alloy high-temperature processed article containing Mg is heated at a high temperature of 200° C. or above, thereafter the surface is etched with an aqueous solution containing a chelating agent, and then at least one surface treatment selected from hydration oxidation treatment, coating type chromating, coating, anodizing, and alternating current electrolysis in an aqueous alkali solution is further carried out. This method can provide a surface-treated aluminum alloy high-temperature processed article having superior anticorrosion and adhesion of coatings and a good surface appearance, and is effective as a pretreatment for further surface treatment.

Abstract: An aluminum material is surface-treated with an aqueous solution containing 0.005 mol/lit. or more of a chelating agent and 5 g/lit. or more of an organic amine and having 100 ppm or less of phosphoric acid radical ion concentration and 500 ppm or less of sulfuric acid radical ion concentration, until its surface has a color tone (S) of:S=(X.sup.2 +(3.388Z-3Y.sup.2).sup.1/2.gtoreq.70wherein X, Y and Z represent the tristimulus values of color.The aluminum material can be surface-treated while setting the treating conditions on the basis of a specific color tone detectable by colorimetry, without relying on experience and intuition. The surface-treated aluminum material can have a good anticorrosion, have good color change preventive properties, a good adhesion of coatings and a beautiful surface appearance.