Patent ID: 6110297
Filing Date: 2000-08-29
Classification: C10M,C10N,C22C,C22F

Abstract:
A method of manufacturing an aluminum alloy sheet having an excellent formability comprising the steps of: homogenizing an aluminum alloy ingot comprising 0.9-1.3 wt. % of Si, 0.4-0.6 wt. % of Mg, 0.05-0.15 wt. % of Mn, 0.01-0.1 wt. % of Ti, with the remainder comprising Al and inevitable impurities, provided that Fe is not present as an impurity in an amount exceeding 0.2 wt. % and Cu is not present as an impurity in an amount exceeding 0.1 wt. %, at a temperature of at least 500.degree. C. for at least 6 hours; cooling the homogenized alloy ingot to a temperature of no higher than 450.degree. C. to begin hot-rolling; finishing hot-rolling in a temperature range of from 200-350.degree. C. to form a hot-rolled alloy plate; performing an intermediate annealing of the hot-rolled alloy plate at a temperature of from 350-420.degree. C.; starting cold-rolling at a draft of 70% or more to form an alloy sheet; applying a solid solution treatment to the alloy sheet by holding it at a temperature of at least 530.degree. C. for no more than 60 seconds and quenching the alloy sheet; forming a chromate film onto the quenched alloy sheet; coating the chromate film with a lubricant composition containing a water-dispersible polyurethane resin and a natural wax; and applying a heat treatment to the coated alloy sheet in a temperature range of from 200-240.degree. C. for no more than 60 seconds.