METHOD FOR THE PRODUCTION OF AN ANODISED, TURNED MECHANICAL PART MADE FROM 6XXX ALLOY AND HAVING LOW ROUGHNESS AFTER ANODISATION

摘要

The invention relates to a method for the production of a mechanical part, comprising the following successive steps: casting of a billet of aluminium alloy with a composition (in weight %) of 0.4 - 3.0 Si; 0.6 - 2.0 Mg; 0.20 - 1.0 Cu; 0.15 - 1.8 Fe; Mn < 0.5; Ni < 1; Ti < 0.15; Cr < 0.35; Bi < 0.8; Pb < 0.4; Zr < 0.04; other elements < 0.05 each and < 0.15 total, the remainder being aluminium; homogenisation of the billet; extrusion of the billet in order to obtain an extruded product; quenching while at extrusion heat; optional cold-deformation and/or straightening, typically by means of pulling and/or drawing, and/or curing of the extruded product; tempering; optional cold-deformation of the extruded product, typically by drawing; machining of the resulting extruded product in order to obtain a turned mechanical part; optional shaping of the resulting mechanical part; anodising of the resulting mechanical part at a temperature of between 15 and 40 °C with a solution comprising between 100 and 250 g/1 sulphuric acid and between 10 and 30 g/1 oxalic acid and between 5 and 30 g/1 of at least one polyol. The anodised turned mechanical parts obtained using the method of the invention have, in particular, advantageous roughness and excellent corrosion resistance and can be used, in particular, as brake pistons or gearbox elements.