Aluminum alloy combining high strength and extrudability, and low quench sensitivity

Abstract

An aluminum alloy includes, in weight percent, 0.70-0.85 Si, 0.14-0.25 Fe, 0.25-0.35 Cu, 0.02-0.08 Mn, 0.75-0.90 Mg, 0.04-0.08 Cr, 0.05 max Zn, and 0.04 max Ti, the balance being aluminum and unavoidable impurities. The minimum Mn content may be 0.03 wt. %, and/or the maximum Mn content may be 0.06 wt. %, in various configurations. The alloy may be suitable for extruding, and may be formed into an extruded alloy product.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This international patent application claims priority to U.S. Provisional Application No. 61 / 909,643, filed Nov. 27, 2014, which is incorporated by reference herein in its entirety and made part hereof.FIELD OF THE INVENTION[0002]The present invention relates generally to an aluminum alloy having high strength and extrudability, and low quench sensitivity, and in some specific aspects, to an aluminum alloy for use in extrusion and other applications, as well as methods for processing such alloys.BACKGROUND[0003]AA6061 is a widely accepted alloy for structural extrusions. There is extensive literature on AA6061 aluminum alloys, including U.S. Pat. Nos. 6,364,969 and 6,565,679. It is typically supplied by a press quenched extrusion route to meet minimum properties associated with the AA6061 T6 temper:[0004]240 MPa YS-260 MPa UTS-8% elongation for section thickness≦0.249″[0005]240 MPa YS-260 MPa UTS-10% elongation for section thickness≧0.250″...

AI Technical Summary

Benefits of technology

[0069]The embodiments described herein can provide advantages over existing alloys, extrusions, and processes, including advantages over typical AA6061 alloys. For example, alloys described herein may have a solution temperature lower than the high Mg-high Si alloys typically used for similar applications, allowing for more efficient use of the alloy additions. Alloys described herein may also have high mechanical strength and improved extrudability over alternate compositions capable of similar strength levels. Further, alloys described herein utilize low-level Cr additions, which provides formation of sufficient Cr dispersoids to promote acceptable toughness, but with sufficiently weak Zener pinning to allow the extrusion to fully recrystallize and to promote a fine grain size. The latter may, in turn, provide superior yield strength for an equivalent ductility, over a wide range of cooling rates. This makes the alloy particularly suitable for thin wall (<6.3 mm or 0.250 in) extrusions, because low cooling rates can be used to minimize distortion in such extrusions which is advantageous for many end use applications requiring complex profiles. Still further, the use of Mn additions within the ranges described herein promotes the formation of alpha Fe during homogenization. Other benefits and advantages are recognizable to those skilled in the art.

Problems solved by technology

with the balance being aluminum and unavoidable impurities.

Images