Strengthening in the new aluminum alloy AA6069

摘要

AA 6069, a new patented aluminum alloy, has been developed for application in hot and cold extrusion and forging. The nominal composition is 0.85% Si, 0.25% Fe, 0.70% Cu, 1.35% Mg, 0.20%Cr, and 0.15% V. Average T6 properties of the ingot withouthot or cold deformation are 410 MPa (59 ksi) ultimate tensile strength (UTS), 375 MPa (54 ksi) yield strength (YS), and 12% elongation. Average properties after hot and/or cold extrusion in the T6 condition range from 394 to 476 MPa (57 to 69 ksi) UTS,353 to 448 MPa (51 to 65 ksi) yield strength, and 14 to 20% elongation. This alloy also has favorable fatigue, corrosion-fatigue, stress-corrosion, and sustained load cracking properties due to a combination of composition, high solidification rate,thermal and mechanical processing, and T6 practice. Careful TEM, SEM, optical metallography, and EDS were used to characterize the precipitation features and the basis for improved mechanical properties over alloys such as 6061 -T6. Current developmentalapplications include cold impact air bag components, high pressure cylinders, automotive wheels, suspension, and drive train parts, and seamless tubing. The alloy is also much more scrap compatible than 2XXX and 7XXX alloys.