7075 Aluminum Alloy Sheet

The core heat treatments for 7075 Aluminum Alloy Sheet (aerospace ultra-hard aluminum) are T6, T73, and T651. Common applications are concentrated in high-strength stress scenarios such as aerospace structural components, precision molds, mechanical tooling fixtures, lightweight automotive parts, and high-end sports equipment.

The most commonly used core heat treatments are T6, T73, and T651.

Processes and Parameters (Manufacturer's Standard Process):

I. T6 State (Standard high strength, most commonly used)

Solution treatment → Water quenching → Artificial aging

Solution treatment

Temperature: 475～500℃ (commonly 480℃)

Holding: Approximately 1 hour per 25mm thickness, ≥2 hours

Requirements: Uniform furnace temperature ±3℃ to prevent overheating

Quenching

Transfer time: ≤15～30 seconds

Medium: Room temperature clean water (20～40℃)

Cooling rate: ≥200℃/min

Artificial aging

Temperature: 120±5℃

Holding: 24 hours

Properties: Tensile strength 550～590MPa, Yield strength 490～530MPa

II. T73 / T74 State (Resistant to stress corrosion, sacrificing a small amount of strength)

Solution treatment + Quenching → Two-stage over-aging

First stage: 105～110℃ × 6～8h

Secondary: 150～165℃ × 16～24h

Strength is about 5～10% lower than T6, but stress corrosion resistance is significantly improved.

III. T651 / T652 state (stress relief, suitable for precision machining)

Based on T6, the following are added:

T651: 1.5～3% tensile stress relief after quenching

T652: Compressive stress relief after quenching

Features: Low residual stress, small deformation during CNC machining, good flatness

IV. O state (annealed soft state, rarely used)

380～420℃ × 2～4h, furnace cooling

Low strength (tensile strength ≈300MPa), only used for very deep drawing/cold bending

Comparison table of different heat treatment states

When choosing 7075 Aluminum Alloy Sheet, the core considerations are the usage environment, processing accuracy, and strength requirements. You can't go wrong by choosing according to the following: For dry indoor environments and those seeking the highest strength... 7075-T6 offers the highest strength and best cost-effectiveness, suitable for general molds, mechanical structures, and tooling fixtures.

For outdoor, humid, salt spray, and seawater corrosive environments, choose 7075-T73. While its strength is slightly lower, it boasts extremely strong resistance to stress corrosion and will not crack even after long-term use.

For precision CNC machining, large-size flat plates, and applications where deformation during machining is a concern, 7075-T651 is the preferred choice. Pre-stretched to relieve stress, it achieves high flatness and virtually no deformation after machining, making it the first choice for precision parts.

For applications requiring minimal bending or stamping, only 7075-O annealed condition should be selected, but this will significantly reduce strength.

For thickness selection, T6/T651 is generally used for thin plates; for medium-thick plates and mold plates, T651 pre-stretched plates are preferred to avoid deformation.