ALUMINUM TUBE - SQUAREAluminum Square Tube is available in alloys 6061-T6 and 6063-T52. Aluminum 6061 is the most widely used alloy, offering better corrosion resistance and weldability than other Aluminum Square Tube, but less strength. Alloy 6063 offers high corrosion resistance and is commonly used for outdoor structural applications such as Aluminum Tube railings and trims.