Forged aluminum alloy having excellent strength and ductility and method for producing the same

2:

• The forged aluminum alloy according to claim 1, further comprising, in mass percent, at least one element selected from the group consisting of:
• Cu in a content of 0.05% to 1.0%;
• Ti in a content of 0.01% to 0.1%;
• and
• Zn in a content of 0.005% to 0.25%.

4:

• A method for producing a forged aluminum alloy having excellent strength and ductility, the method comprising:
• preparing an aluminum alloy ingot comprising, in mass percent:
• Si in a content of 0.7% to 1.5%;
• Mg in a content of 0.6% to 1.2%;
• Fe in a content of 0.01% to 0.5%;
• and
• at least one element selected from the group consisting of:
• Mn in a content of 0.05% to 1.0%;
• Cr in a content of 0.01% to 0.5%;
• and
• Zr in a content of 0.01% to 0.2%, and
• Al and inevitable impurities;
• subjecting the aluminum alloy ingot sequentially to homogenization and hot-forging to give a forged material;
• and
• subjecting the forged material sequentially to solution treatment, quenching, warm working, and artificial aging in the specified sequence,
• wherein:
• the forged material after artificial aging has a microstructure in an observation plane at a center of a thickness in a thickest portion of the forged material;
• the microstructure has a dislocation density of from 1.0×1014 to 5.0×1016 per square meter on average as measured by X-ray diffractometry;
• the microstructure comprises small angle grain boundaries with a tilt angle of 2° to 15° in an average proportion of 50% or more as measured by SEM-EBSD, the small angle grain boundaries being present around grains having a misorientation of 20 or more;
• and
• the microstructure comprises precipitates in an average number density of 5.0×102 per cubic micrometer or more, the precipitates being measurable by a TEM at 300000-fold magnification.