Aluminum Round Rod | Bar                                               2011 Aluminum Alloy is a free cutting alloy, considered a screw machine stock, due to its fine chips and excellent finishing characteristics. It offers good strength and average formability. 2024 Aluminum Alloy is slighlty more difficult to machine than 2011 but offers enough strength for aircraft fittings, bolts and other high strength applications. 6061 Aluminum Alloy is the most versatile of the the alloys with good strength, workabilty, corrosion resistance and welding. It is less machinable than the 2000 series.