6061 Aluminum Overview
6061 aluminum is a precipitation-hardened grade primarily alloyed with magnesium and silicon. It offers a well-balanced combination of mechanical strength, corrosion resistance, and excellent weldability, making it one of the most widely used aluminum alloys for general-purpose engineering and industrial applications. Density is 2.70 g per cubic centimeter.
Chemical Composition
Limits are silicon 0.40 to 0.80 percent, iron 0.70 percent maximum, copper 0.15 to 0.40 percent, manganese 0.15 percent maximum, magnesium 0.80 to 1.20 percent, chromium 0.04 to 0.35 percent, zinc 0.25 percent maximum, titanium 0.15 percent maximum, others each 0.05 and total 0.15 percent maximum, with aluminum as balance.
Mechanical Properties by Temper
6061-O, the annealed condition, has ultimate tensile strength up to 125 MPa, yield up to 55 MPa, and elongation of 25 to 30 percent for extensive forming. 6061-T4, solution heat treated and naturally aged, has tensile of at least 207 MPa and yield of at least 110 MPa with about 16 percent elongation. 6061-T6, solution heat treated and artificially aged, has tensile of at least 290 MPa and yield of at least 241 MPa, with elongation of at least 8 percent for thin sections and 10 percent for thicker sections. 6061-T651 provides the same strength with stress relief for dimensional stability.
Welding Characteristics
6061 is highly weldable using TIG and MIG processes. After welding, the heat-affected zone typically exhibits properties similar to 6061-O, with an approximate 80 percent reduction in strength, but the entire component can be reheat-treated to restore T4 or T6 properties.
Applications
6061 is used for aircraft wings and fuselages, yacht and small boat construction, bicycle frames, automotive, ATV, and industrial equipment. Extrusions serve structural frames, transportation components, and architectural systems, while forgings serve automotive components, ATV parts, and heavy-duty industrial hardware.
Frequently Asked Questions
Q: What is the yield strength of 6061-T6?
A: At least 241 MPa, typically 276 MPa.
Q: What temper is softest?
A: 6061-O, with 55 MPa yield for maximum formability.
Q: What is the difference between T6 and T651?
A: T651 adds stress relief by stretching for better dimensional stability.
Q: Does welding weaken 6061?
A: The heat-affected zone loses about 80 percent strength unless reheat treated.
Q: What forms are available?
A: Sheet, plate, bar, tube, extrusions, and forgings.
Q: Why is 6061 so widely used?
A: Balanced strength, corrosion resistance, weldability, and cost.
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