Aluminum alloy sheet excellent in baking finish hardenability

摘要

This aluminum alloy sheet has increased BH properties under low-temperature short-time-period conditions after long-term room-temperature aging by means of causing aggregates of specific atoms to be contained having a large effect in BH properties, the distance between atoms being no greater than a set distance, and containing either Mg atoms or Si atoms measured by 3D atom probe field ion microscopy in a 6000 aluminum alloy sheet containing a specific amount of Mg and Si.

主权项

1. An Al—Mg—Si-based aluminum alloy sheet, comprising:
Mg: 0.2-2.0 mass %, Si: 0.3-2.0 mass %, and Al, wherein the Al—Mg—Si based aluminum alloy sheet is obtained by a process comprising a reheating treatment, in which a retention time at a reheating temperature of 70-130° C. is 0.2-1 hr; and an average number density of aggregates of atoms satisfying the following conditions is at least 1.0×105 pieces/μm3:
each of the aggregates measured by a three-dimensional atom probe field ion microscope comprises either Mg atoms or Si atoms or both of them by 30 pieces or more in total, andwhen any atom of the Mg atoms or the Si atoms comprised in each aggregate is made as a reference atom, a distance between the reference atom and at least one neighboring Mg or Si atom of the reference atom is 0.75 nm or less.