Aluminum alloy sheet having good formability

Abstract

Provided is a 6000-series aluminum alloy sheet having good formability for an automotive body panel, which can be manufactured without greatly varying an existing composition or an existing manufacturing condition. The amount of solute Si and the amount of solute Cu in an Al—Mg—Si aluminum alloy sheet are increased in a balanced manner, so that the sheet has a dislocation density within a specific range when tensile deformation in a low-strain region is applied to the sheet. This suppresses localization of dislocations introduced into a material due to tensile deformation during press forming into an automotive body panel, and allows dislocations to be evenly multiplied from the low-strain region to a high-strain region. Consequently, uneven deformation is suppressed during forming into the automotive body panel, and good work hardenability is exhibited.

What is claimed is: 
     
         1 . An aluminum alloy sheet having good formability, comprising an Al—Mg—Si aluminum alloy sheet that contains, by mass percent, Si: 0.30 to 2.0%, Mg: 0.20 to 1.5%, Cu: 0.05 to 1.0%, Mn: 1.0% or less (not including 0%), and Fe: 1.0% or less (not including 0%), the remainder consisting of Al and inevitable impurities, wherein an amount of solute Si is 0.30 to 2.0% and an amount of solute Cu is 0.05 to 1.0% in a solution of the aluminum alloy sheet, the solution being separated by a hot-phenol residue extraction method, and when tensile deformation with a strain of 5% is applied to the aluminum alloy sheet in a rolling direction of the aluminum alloy sheet, dislocation density in a rolled surface of the aluminum alloy sheet is 6.0×10 14  to 12×10 14  m −2  in average, the dislocation density being measured by X-ray diffraction. 
     
     
         2 . The aluminum alloy sheet according to  claim 1 , wherein the aluminum alloy sheet further contains one or more of Cr: 0.3% or less (not including 0%), Zr: 0.3% or less (not including 0%), V: 0.3% or less (not including 0%), Ti: 0.1% or less (not including 0%), Zn: 1.0% or less (not including 0%), Ag: 0.2% or less (not including 0%), and Sn: 0.15% or less (not including 0%). 
     
     
         3 . The aluminum alloy sheet according to  claim 1 , wherein a yield ratio is 0.56 or less, the yield ratio being defined by a ratio of 0.2% proof stress to tensile strength (0.2% proof stress/tensile strength) of the aluminum alloy sheet, and a total elongation is 26% more.