PRODUCTION OF ALUMINUM ALLOY SHEET EXCELLENT IN FORMABILITY, BAKING FINISH HARDENABILITY, CHEMICAL CONVERTIBILITY AND CORROSION RESISTANCE

摘要

PROBLEM TO BE SOLVED: To obtain an aluminum alloy sheet excellent in formability, baking finish hardenability, chemical convertibility and corrosion resistance by subjecting a sheet of an alloy consisting of specific percentages of elements to solution heat treatment and hardening treatment, to heat treatment under specific conditions, and then to galvanizing where the amounts of Pb, As, Sn, Cd, Ti, and Cu, as impurities, in a plating layer are regulated to specific values or below, respectively. ;SOLUTION: The alloy sheet has a composition consisting of, by mass, 0.65-1.0% Mg, 0.35-0.9% Si, 0.1-1.0% Cu, 0.01-0.3% Sn, and the balance Al with inevitable impurities and satisfying -2.04Mg-7Si1.0. This alloy sheet is subjected to solution heat treatment and hardening treatment and then subjected, within 24hr, to heat treatment at 70-150°C for 0.5-50hr. Further, a galvanizing layer is formed on the alloy sheet. At this time, the upper limits of the concentrations of Pb, As, Cd, Ti, and Cu, as impurities, in the plating layer are specified to ≤150ppm, ≤100ppm, ≤1000ppm, ≤100ppm, and ≤500ppm, respectively.;COPYRIGHT: (C)1998,JPO