7075 is the high-strength aluminum. In T6 it is close to the strength of mild steel at about a third of the weight, and it machines beautifully. The trade-offs are real: it does not fusion weld, it does not bend well, and it corrodes more readily than 6061. For machined parts that carry high loads, molds, fixtures and tooling, it is the grade to reach for. We source 7075 plate and bar and arrange saw cutting to your sizes.
What 7075 aluminum is
7075 is a 7xxx-series alloy. Zinc is the main alloying element at roughly 5.6%, with about 2.5% magnesium and 1.6% copper. The zinc and magnesium form precipitates during heat treatment that give it far higher strength than 6061.
It was developed for aircraft structure and is still widely used there. In a job shop, it is the alloy for parts where 6061 would bend or wear too quickly.
7075-T6 properties
| Property | Value | What it means in the shop |
|---|---|---|
| Tensile strength | 83 ksi typical | Roughly double 6061-T6 |
| Yield strength | 73 ksi typical | Resists permanent bending under high load |
| Hardness | About 150 Brinell | Wears and dents far less than 6061 |
| Density | 0.101 lb/in³ (2.81 g/cm³) | A little heavier than 6061, still light |
| Weldability | Not recommended (fusion) | Hot cracks and loses strength; design to bolt |
| Machinability | Very good | Short chips, excellent finish, holds tolerance |
| Corrosion resistance | Fair | Anodize or coat; T73 tempers resist stress corrosion |
Typical values for T6 and T651. Stiffness is the same as other aluminum alloys.
Typical uses
- High-load machined parts: arms, links, clamps and brackets
- Molds, fixtures and tooling plate
- Aerospace and aircraft structural parts
- Firearm components and sporting equipment
- Gears, shafts and wear parts where weight matters
Common tempers
T6 is solution heat treated and aged to peak strength. T651 is T6 plate or bar that has been stretched for stress relief; it is the one to order for machining, because it stays flat when you remove material. T7351 and T73 are over-aged tempers that give up some strength for much better resistance to stress-corrosion cracking, called out on aerospace and critical outdoor parts. O is annealed and rarely used outside forming before heat treatment.
Plate and round bar are the common forms. Sheet exists but is far less common than in 6061 or 5052.
7075 vs 6061 aluminum
7075 is roughly twice as strong as 6061 and machines even better. 6061 welds, bends a little, anodizes more evenly and resists corrosion better, and it is usually easier to source in a wide range of shapes. 7075 also costs more by the pound. One point people miss: both have the same stiffness, so if a part is failing by flexing rather than yielding, switching to 7075 will not help. Add section instead.
| 7075-T6 | 6061-T6 | |
|---|---|---|
| Tensile / yield (typical) | 83 / 73 ksi | 45 / 40 ksi |
| Stiffness (modulus) | About 10.4 million psi | About 10.0 million psi |
| Welding | Not recommended | Good |
| Machining | Very good | Good |
| Corrosion resistance | Fair | Good |
| Available shapes | Mostly plate and bar | Plate, bar, sheet, tube, extrusions |
Welding and machining 7075
Do not plan to fusion weld 7075. It is prone to hot cracking, and the heat destroys the temper that gives it strength. Design joints to be bolted, pinned or bonded. If a drawing calls for welded 7075, check with the engineer before you cut.
Machining is where 7075 shines. It produces short chips, takes a fine finish and holds tight tolerance. Run it like 6061 with a little more rigidity. Use T651 for anything heavily pocketed, and rough, flip and finish to manage residual stress on thin-wall parts.