Production manner null of the high strength aluminum alloy extruded pipe for the front fork outer tube of the motorcycle which is superior in resistance stress corrosion crack

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an aluminum alloy extruded tube excellent in stress corrosion cracking-resistance, having high strength and suit able as the front fork outer tube of an automatic two wheeler in particular. ;SOLUTION: An aluminum alloy extruded tube having a compsn. contg., by weight, 3.0 to 10.0% Zn, 0.5 to 3.0% Mg and 0.05 to 3.0% Cu, contg. one or more kinds among ≤0.3% Cr, ≤0.3% Mn and ≤0.3% Zr and one or more kinds of ≤0.05% Ti and ≤0.005% B, in which the contents of Fe and Si as impurities are respectively limited to ≤0.2%, and the balance aluminum is subjected to solution treatment and quenching treatment, is subjected to natural aging for ≥100hr, is thereafter subjected to heat treatment at 150 to 250°C for 30sec to 10min in such a manner that the heating rate from 100°C to a prescribed heat treating temp. is regulated to ≥1°C/sec and is finally subjected to artificial aging treatment.;COPYRIGHT: (C)1998,JPO