Aluminum alloy 6061 is one of the most commonly used types of aluminum due to its excellent corrosion resistance, machinability, formability, and weldability. However, within the 6061 family there are different options for temper or heat treatment that can significantly impact the alloy’s mechanical properties and suitability for different applications. Two of the most prevalent variants are 6061-T6 and 6061-T4 – but which one should you use?
What’s Aluminum 6061-T4?
Aluminum 6061-T4 is also a heat-treatable aluminum alloy that is commonly used for structural applications. The key difference between 6061-T4 and 6061-T6 is the temper, or heat treatment process designation. 6061-T4 alloy undergoes solution heat treatment, but not artificial aging like T6 – it is allowed to slowly cool and age naturally. This results in a material that is stronger than the raw aluminum alloy, but with lower strength properties than 6061-T6. Specifically, 6061-T4 has a lower tensile yield strength of around 41,000 psi compared to 48,000 psi for T6. However, 6061-T4 maintains good corrosion resistance from the heat treatment while being easier to machine and form than T6 due to its lower strength. Its combination of properties makes 6061-T4 a versatile and cost-effective choice for various structural components and assemblies.
What Are The Advantages Of 6061-T4?
Machinability – 6061-T4 is easier to machine, drill, mill, etc. due to its lower strength relative to T6. This makes it cheaper to fabricate complex parts.
Formability – As a softer alloy, 6061-T4 can be more easily formed into complex shapes through bending, stretching and other traditional metalworking compared to harder T6.
Weldability – 6061-T4 has better weldability than higher strength T6 since heat from welding is less likely to cause cracking or defects in the weaker T4 temper.
Cost – The T4 temper is less expensive to produce than T6 as it doesn’t require artificial aging in an oven.
Corrosion resistance – While not as resistant as T6, 6061-T4 still provides good corrosion protection for many applications.
Durability – It maintains strength suitable for general industrial/vehicle use where highest strength isn’t required.
Availability – 6061-T4 is the most widely used and stocked 6000 series alloy, available from nearly any supplier.
Familiarity – Existing knowledge and fabrication experience with 6061-T4 outstrips other alloys/tempers due to decades of use.
Repairability – Damaged 6061-T4 parts can be more easily/cheaply repaired by welding compared to harder T6.
What Are The Applications Of 6061-T4?
Automotive components – Parts like drive shafts, suspension arms, pedals, brackets benefit from its machinability.
Industrial equipment – Frames, housings, guards for machines use 6061-T4’s workability and durability.
Boats and ships – Decks, racks, ladders, fittings are often made from marine-grade 6061-T4.
Bicycles – Frames, forks, handlebars, pedals utilize the alloy’s strength and low weight.
Ladders and scaffolding – 6061-T4 has the properties needed for long-lasting infrastructure.
Appliances – Washers, dryers, refrigerators use 6061-T4 for durable internal components.
Furniture – Tables, desks, chairs are common applications that require fabrication.
Signage and displays – Outdoor enclosure framing, shelving rely on its corrosion resistance.
Piping and ductwork – Low-pressure HVAC systems frequently employ 6061-T4 tubing.
General fabrication – Its workability allows 6061-T4 to be used for myriad DIY and prototype parts.
Firearms – Receivers, actions of some guns leverage the alloy’s machinability.
What’s Aluminum 6061-T6?
T6 is a type of aluminum alloy that is often used in aerospace and transportation applications. The 6061 designation refers to the main alloying elements of magnesium and silicon, while the -T6 indicates that the alloy has undergone a specific heat treatment process. -T6 alloys start as castings that are then solution heat treated and artificially aged, which results in a material that is heat-treatable to a high strength-to-weight ratio while maintaining good machining and welding properties. This process provides 6061-T6 with useful mechanical properties like increased strength, hardness, and corrosion resistance, making it a versatile and widely used aluminum alloy.
What Are The Advantages Of 6061-T6?
High strength-to-weight ratio. The heat treatment process gives 6061-T6 increased tensile and yield strength compared to other aluminum alloys, allowing it to support heavy loads without being too heavy.
Good machinability. While stronger than non-heat treated alloys, 6061-T6 can still be easily machined, drilled, turned, milled, etc. which is important for fabrication.
Corrosion resistance. The alloying elements in 6061 provide natural resistance that is further enhanced by the protective oxide layer formed during heat treatment.
Fatigue and creep resistance. The increased strength of 6061-T6 improves its ability to withstand cyclic or long-term stresses without fracturing.
Formability. It can be bent, forged, and otherwise shaped using standard metalworking processes.
Weldability. With proper techniques, 6061-T6 can be easily joined by welding, which is critical for vehicle and structural applications.
Cost-effectiveness. Despite its advantages, 6061-T6 remains more affordable than other high-strength alloys like 7000 series.
Availability. As one of the most common alloys, 6061-T6 is readily available around the world from numerous suppliers.
What Are The Aplications Of 6061-T6?
Aircraft structures – It’s used extensively in aircraft fuselages, wings, support beams, and other load-bearing parts due to its high strength to weight ratio.
Automotive components – Drive shafts, suspension parts, wheels, pedals, and more take advantage of 6061-T6’s durability.
Boats and ships – Marine grade 6061-T6 is often the material of choice for decks, bulkheads, masts, and other nautical applications.
Industrial equipment – Anything from machine frames to construction equipment benefits from 6061-T6’s perfect balance of strength and workability.
Bridges and infrastructure – Its corrosion resistance makes it suitable for railing, struts, trusses and other long-term outdoor applications.
Pressure vessels – Tanks, cylinders, valves and piping use 6061-T6 when high-pressure integrity is required.
Building and construction – Curtain walls, window frames, handrails, and other architectural elements commonly employ 6061-T6.
Consumer products – Anything from bikes to furniture to appliances may incorporate 6061-T6.
Firearms – Some gun parts like receivers and barrels are produced from precision-machined 6061-T6.
Aluminum 6061-T6 vs 6061-T4, Which Is Better
| Property | 6061-T6 | 6061-T4 |
|---|---|---|
| Temper Process | Solution heat treated and artificially aged | Solution heat treated and naturally aged |
| Strength | Higher | Lower |
| Tensile Yield Strength (psi) | 48,000 | 41,000 |
| Machinability | More difficult | Easier |
| Formability | More difficult | Easier |
| Weldability | More difficult | Easier |
| Corrosion Resistance | Higher | Lower |
| Fatigue Resistance | Higher | Lower |
| Cost | Higher | Lower |
| Applications | Aircraft structures, automotive, pressure vessels, etc. requiring high strength | Industrial equipment, appliances, signs, piping, etc. where easier forming/joining is important |