7075 aluminum alloy forged discs represent the pinnacle of aerospace-grade aluminum components, offering exceptional strength, fatigue resistance, and stress distribution for critical rotating and structural applications:

Primary Alloying Elements:

Zinc (Zn): 5.1-6.1% (principal strengthening element)

Magnesium (Mg): 2.1-2.9% (enhances precipitation hardening)

Copper (Cu): 1.2-2.0% (improves strength and stress resistance)

Chromium (Cr): 0.18-0.28% (corrosion resistance and grain structure control)

Base Material:

Aluminum (Al): ≥87.1% (balance)

Controlled Impurities:

Iron (Fe): ≤0.50% max

Silicon (Si): ≤0.40% max

Manganese (Mn): ≤0.30% max

Titanium (Ti): ≤0.20% max

Other elements: ≤0.05% each, ≤0.15% total

Premium Forging Process:

Melt Preparation:

Primary high-purity aluminum (99.7% minimum)

Precise alloying element additions with ±0.1% tolerance

Advanced filtration through ceramic foam filters (30-40 ppi)

SNIF degassing treatment (hydrogen < 0.10 ml/100g)

Grain refinement with Al-Ti-B master alloy

Direct-chill (DC) semi-continuous casting

Homogenization:

460-480°C for 24-36 hours

Uniform temperature control: ±5°C

Controlled cooling rate: 15-25°C/hour

Dissolution of coarse intermetallics

Microsegregation elimination

Billet Preparation:

Surface conditioning (scalping)

Ultrasonic inspection (100% volumetric)

Preheating: 380-400°C for uniform temperature

Forging Sequence:

Open-die preforming: 380-410°C

Closed-die finish forging: 360-390°C

Hydraulic press capacity: 2,000-10,000 tons

Computer-controlled ram speed and pressure

Multi-stage forging for optimal grain flow

Minimum reduction ratio: 3:1

Solution Heat Treatment:

465-485°C for 1-4 hours (thickness dependent)

Temperature uniformity: ±3°C

Rapid transfer to quenching medium (<10 seconds)

Quenching:

Polymer-enhanced water quenchant

Controlled agitation for uniform cooling

Minimum cooling rate: 100°C/sec at surface

Stress Relief:

Controlled stretching (1-3% plastic deformation)

Alternatively, compressive stress relief

Artificial Aging (T6/T73 Tempers):

T6: 120°C for 24 hours

T73: Two-stage aging (107°C for 6-8 hours, followed by 163-177°C for 24-30 hours)

Temperature uniformity: ±3°C

Final Processing:

Precision machining to near-net shape

Surface treatment

Nondestructive testing

Dimensional verification

Full process traceability with computerized quality monitoring at all stages.

 

 

 

Property	T6 Temper	T73 Temper	T7351 Temper	Test Method
Ultimate Tensile Strength	570-595 MPa	505-545 MPa	510-550 MPa	ASTM E8
Yield Strength (0.2%)	495-525 MPa	425-470 MPa	435-480 MPa	ASTM E8
Elongation (2 inch)	8-12%	10-14%	10-14%	ASTM E8
Hardness (Brinell)	150-165 HB	140-155 HB	140-155 HB	ASTM E10
Fracture Toughness (K1C)	24-29 MPa√m	31-37 MPa√m	29-35 MPa√m	ASTM E399
Fatigue Strength (10⁷ Cycles)	160-190 MPa	145-170 MPa	150-175 MPa	ASTM E466
Shear Strength	330-350 MPa	290-315 MPa	295-325 MPa	ASTM B769
Compressive Yield Strength	520-550 MPa	455-495 MPa	465-505 MPa	ASTM E9
Modulus of Elasticity	71.7 GPa	71.7 GPa	71.7 GPa	ASTM E111

 

Property Distribution:

Radial vs. Tangential: <5% variation in strength properties

Surface to center variation: <8% for discs up to 150mm thickness

Minimum properties guaranteed in all critical orientations

Superior isotropy compared to rolled plate or extruded bar

Stress corrosion cracking resistance (T73): >200 MPa threshold stress

 

Key Microstructural Features:

Grain Structure:

Fine, equiaxed recrystallized grains

ASTM grain size 6-8 (45-22μm)

Uniform grain distribution across section

Controlled grain flow pattern following forging contours

Precipitate Distribution:

MgZn₂ (η/η’) strengthening precipitates: 5-15nm

CuMgAl₂ (S-phase) precipitates: Uniformly distributed

Al₇Cu₂Fe intermetallics: Controlled size and distribution

Al₁₂Mg₂Cr dispersoids: 50-200nm for recrystallization control

Texture Development:

Balanced texture with minimized directionality

Forging-induced fiber texture optimized for isotropic properties

Special fiber texture tailored for high fatigue resistance

Special Features:

Minimal precipitate-free zones (PFZs) at grain boundaries

Controlled distribution of coarse intermetallics

Fine dispersoid distribution for recrystallization control

Optimized grain boundary character distribution

 

Parameter	Standard Range	Precision Tolerance	Commercial Tolerance	Test Method
Diameter	50-1500 mm	±0.5mm up to 150mm	±1.0mm up to 150mm	CMM
		±0.3% above 150mm	±0.6% above 150mm
Thickness	15-300 mm	±0.5mm up to 50mm	±1.0mm up to 50mm	Micrometer
		±1.0% above 50mm	±1.5% above 50mm
Flatness	N/A	0.5mm/m	1.0mm/m	Dial gauge
Surface Roughness	N/A	3.2 μm Ra max	6.3 μm Ra max	Profilometer
Parallelism	N/A	0.5mm	1.0mm	CMM
Concentricity	N/A	0.5mm	1.0mm	CMM
Bolt Circle Diameter	As specified	±0.2mm	±0.5mm	CMM

Standard Available Forms:

Diameters: 50mm to 1500mm

Thickness: 15mm to 300mm

Profile variations: Flat, stepped, contoured

Surface conditions: As-forged, machined, heat-treated

Near-net shape capabilities for reduced machining

Custom forgings with integral features (bosses, lugs, etc.)

 

 

 

Temper Code	Process Description	Optimal Applications	Key Characteristics
T6	Solution heat treated and artificially aged	High-strength applications	Maximum strength and hardness
T651	T6 + stress relieved by stretching	Critical structural components	Improved stress distribution
T73	Solution heat treated and overaged	Stress corrosion critical applications	Superior SCC resistance with reduced strength
T7351	T73 + stress relieved by stretching	Critical aerospace components	Excellent balance of properties
T76	Modified overaging treatment	Balanced property requirements	Compromise between T6 and T73

 

Temper Selection Guidance:

T6/T651: Maximum strength and fatigue resistance requirements

T73/T7351: Stress-corrosion critical applications

T76: Balanced properties for general aerospace applications

 

Operation	Tool Material	Recommended Parameters	Comments
Turning	Carbide, PCD	Vc=150-300 m/min, f=0.1-0.3 mm/rev	Sharp tools essential
Face Milling	Carbide, PCD	Vc=200-400 m/min, fz=0.1-0.2 mm/tooth	High-positive rake angles
Drilling	Carbide, TiAlN coated	Vc=80-120 m/min, f=0.15-0.30 mm/rev	Through-coolant drills preferred
Tapping	HSS-E-PM, TiCN coated	Vc=15-25 m/min	Form taps for critical threads
Reaming	Carbide, PCD	Vc=60-90 m/min, f=0.2-0.4 mm/rev	H7 tolerance achievable
Boring	Carbide, PCD	Vc=200-300 m/min, f=0.1-0.3 mm/rev	Balanced boring bars for vibration control

 

Fabrication Guidance:

Machinability Rating: 70% (1100 aluminum = 100%)

Surface Finish: Good (Ra 0.8-3.2μm achievable)

Chip Formation: Short to medium chips with proper tooling

Coolant: Water-soluble emulsion (8-10% concentration)

Tool Wear: Moderate with proper parameters

Cutting Forces: Higher than other aluminum alloys

Material Removal Rate: Up to 2000 cm³/min possible with robust setups

Residual Stress Control: Critical for aerospace components

Thin-wall Machining: Careful approach to minimize distortion

Heat Generation: Monitor to avoid localized overheating

 

Environment Type	Resistance Rating	Protection Method	Expected Performance
Industrial Atmosphere	Fair	Anodizing + paint	3-5 years with maintenance
Marine Environment	Poor	Anodizing + chromate + paint	2-3 years with maintenance
High Humidity	Fair	Anodizing Type II	1-2 years without additional protection
Stress Corrosion	Poor in T6, Good in T73	Proper temper selection	Application specific
Exfoliation	Poor in T6, Good in T73	Proper temper selection + protection	Critical for marine applications
Galvanic Corrosion	Poor with carbon steels	Isolation or sacrificial protection	Requires careful design

 

Surface Protection Options:

Anodizing:

Type I (Chromic): 2-8μm (aerospace grade)

Type II (Sulfuric): 10-25μm (general purpose)

Type III (Hard): 25-75μm (wear resistance)

Sealing options: Hot water, dichromate, nickel acetate

Conversion Coatings:

Chromate per MIL-DTL-5541 Class 1A

Non-chromium alternatives for environmental compliance

Painting Systems:

Epoxy primer + polyurethane topcoat

Aerospace-qualified systems per OEM specifications

Advanced Protection:

Sol-gel pretreatments

Plasma electrolytic oxidation

Ion vapor deposition (IVD) aluminum coating

 

 

 

Property	Value	Design Consideration
Density	2.81 g/cm³	Weight calculation for rotating components
Melting Range	477-635°C	Heat treatment limitations
Thermal Conductivity	130-150 W/m·K	Thermal gradient analysis
Electrical Conductivity	33-40% IACS	Electrical applications design
Specific Heat	860 J/kg·K	Thermal mass calculations
Thermal Expansion (CTE)	23.4 ×10⁻⁶/K	Thermal stress analysis
Young’s Modulus	71.7 GPa	Deflection and stiffness calculations
Poisson’s Ratio	0.33	Structural analysis parameter
Damping Capacity	Low	Vibration analysis for rotating components

 

Design Considerations:

Operating Temperature Range: -60°C to +120°C

Property Retention: Excellent below 100°C, gradual degradation above

Stress Relaxation: Minimal below 100°C

Fatigue Life: Superior due to forged microstructure

Notch Sensitivity: Moderate (improved in T73 temper)

Cryogenic Performance: Good strength retention at low temperatures

Spin Testing Requirements: Typically 115-120% of maximum design speed

 

Standard Testing Procedures:

Chemical Composition:

Optical emission spectroscopy

X-ray fluorescence analysis

Verification of all major elements and impurities

Mechanical Testing:

Tensile testing (radial, tangential, and axial directions)

Hardness testing (Brinell, multiple locations)

Impact testing (when required)

Fatigue testing (for critical applications)

Nondestructive Testing:

Ultrasonic inspection (100% volumetric)

Penetrant inspection (100% surface)

Eddy current testing (surface and near-surface)

Radiographic testing (when required)

Microstructural Analysis:

Grain size determination

Intermetallic particle evaluation

Precipitate distribution

Fiber flow pattern verification

Dimensional Inspection:

CMM (Coordinate Measuring Machine) verification

Geometric dimensioning and tolerancing (GD&T)

Runout and flatness measurements

Profile verification for contoured discs

Standard Certifications:

Material Test Report (EN 10204 3.1)

Chemical analysis certification

Mechanical properties certification

Heat treatment certification

Nondestructive testing certification

Traceable to aerospace standards (AMS, ASTM, etc.)

 

Primary Applications:

Aerospace Components:

Aircraft landing gear components

Aero-engine turbine discs and fan discs

Structural fittings and brackets

Aircraft structural frames and spar fittings

Defense Applications:

Missile components

Critical structural elements for weapon systems

Armored vehicle transmission components

High-stress parts for tactical equipment

High-Performance Automotive:

Racing wheel hubs and drivetrain components

Critical suspension system components

Brake disc hats

Aerospace-grade fastener bases

Industrial Equipment:

High-stress couplings for heavy machinery

Compressor impellers

High-pressure parts for pumps and valves

Test equipment fixtures

Design Advantages:

Exceptional strength-to-weight ratio

Superior fatigue life and damage tolerance

Optimized grain flow and microstructure from forging process

High reliability and consistency

Good machinability

Excellent dimensional stability

Reliable performance in high-stress applications

Extensive material database for engineering design

Customizable to specific requirements

Design Limitations:

Relatively higher cost

Relatively poorer corrosion resistance in T6 temper

Not suitable for welding applications

Higher sensitivity to notches and surface defects

Limited formability

Not recommended for prolonged use above 120°C

Requires specialized forging and heat treatment equipment

Longer manufacturing lead times