ALUMINUM ALLOY ROLLED SHEET FOR FORMING EXCELLENT IN STRESS CORROSION CRACKING RESISTANCE AND ITS MANUFACTURE

摘要

PURPOSE: To provide an aluminum alloy rolled sheet excellent in strength and formability as well as stress corrosion cracking resistance and suitable for an automotive body seat or the like and to provide its manufacturing method. ;CONSTITUTION: The objective rolled sheet has a componental compsn. fundamentally constituted of 3.0 to 7.0% Mg, 1.0 to 2.0% Zn, ≤0.1% Cu, ≤0.4% Fe and ≤0.2% Si, and the balance substantial Al, and, in which the average size of precipitates (η phase, β phases and T phases) on the grain boundaries caused by Mg or Zn is regulated to the range of 0.2 to 2μm. After the rolling, it is subjected to solution annealing of holding it at 280 to 580°C for ≤5hr and executing cooling at ≥10°C/min cooling rate and is moreover subjected to final annealing (precipitating treatment) of executing heating at 180 to 300°C for 30min to 24hr to obtain the precipitating state.;COPYRIGHT: (C)1993,JPO&Japio