7075 aluminum alloy (AMS 4045, ASTM B247) represents a premium high-strength aerospace material optimized for critical aircraft structural components. The ultra-thick forged plate variant provides exceptional strength-to-weight performance through specialized processing:

Primary Alloying Elements:

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

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

Copper (Cu): 1.2-2.0% (strength enhancement)

Chromium (Cr): 0.18-0.28% (corrosion resistance)

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

Ultra-Thick Forging Process:

Premium Ingot Production:

Vacuum-degassed primary aluminum

Triple filtration through ceramic filters

Direct-chill (DC) casting with controlled cooling

Homogenization Treatment:

460-480°C for 24-48 hours (thickness-dependent)

Computer-controlled thermal profiles

Surface Conditioning:

Scalping minimum 12mm per surface

Ultrasonic inspection for internal quality

Multi-directional Forging:

Initial breakdown: 410-430°C

Final forging: 360-380°C

Deformation ratio: 4:1 minimum

Multi-directional working for optimal isotropy

Solution Heat Treatment:

465-480°C for thickness-specific duration

Computer-monitored temperature uniformity

Quenching:

Polymer quenchant with controlled concentration

Agitation rate: 3-5 m/s minimum

Core cooling rate: >50°C/sec minimum

Controlled Stretching:

1.5-3.0% permanent deformation

Artificial Aging:

T651/T7351 tempers: Multi-stage aging cycle

Temperature control: ±2°C maximum deviation

All processing maintains complete traceability with digital monitoring throughout manufacturing.

 

 

 

Property	Minimum (T651)	Typical (T651)	Test Standard
Ultimate Tensile Strength	530 MPa	565-590 MPa	ASTM E8/E8M
Yield Strength (0.2%)	455 MPa	495-520 MPa	ASTM E8/E8M
Elongation (2 inch)	7%	9-12%	ASTM E8/E8M
Fracture Toughness (K₁c)	26 MPa√m	28-31 MPa√m	ASTM E399
Shear Strength	330 MPa	340-360 MPa	ASTM B769
Bearing Strength (e/D=2.0)	785 MPa	800-850 MPa	ASTM E238
Fatigue Strength (10⁷)	160 MPa	170-190 MPa	ASTM E466
Hardness (Brinell)	140 HB	145-155 HB	ASTM E10

Through-Thickness Performance:

Property variation <8% between surface and core (up to 250mm thickness)

Directionality ratio (L:LT:ST): 1.00:0.95:0.85 for tensile strength

Core-to-surface hardness variation: ≤10 HB maximum

 

 

 

Critical Processing Parameters:

Grain Structure Control:

Unrecrystallized, fibrous grain morphology

Cr-dispersoid pinning of grain boundaries

Specialized thermal profile for thick sections

Precipitate Engineering:

MgZn₂ (η/η’) precipitate size: 5-15nm

Al₂CuMg (S-phase) distribution

Al₇Cu₂Fe intermetallic control

Quench Rate Optimization:

Polymer concentration: 12-18%

Agitation system: Multi-directional high-velocity flow

Minimum center cooling rate: 55°C/sec

Microstructural Characteristics:

Grain Size: ASTM 8-10 (15-30μm)

Grain Aspect Ratio: 3:1 to 5:1 (L:ST)

Recrystallized Volume Fraction: <15% maximum

Precipitate Density: >10¹⁷/cm³

Inclusion Rating: ≤0.3 per ASTM E45

 

 

 

Parameter	Standard Range	Aerospace Tolerance	Commercial Tolerance
Thickness	100-300 mm	±0.8mm or ±0.5%*	±1.5mm or ±1.0%*
Width	1000-2500 mm	±3 mm	±6 mm
Length	2000-8000 mm	±5 mm	±12 mm
Flatness	N/A	0.1% of length	0.3% of length
Parallelism	N/A	0.2% of thickness	0.5% of thickness
Surface Roughness	N/A	3.2 μm Ra max	6.3 μm Ra max

*Whichever is greater

 

Ultra-Thick Specific Parameters:

Density: 2.81 g/cm³ (±0.02)

Weight Formula: Thickness(mm) × Width(m) × Length(m) × 2.81 = Weight(kg)

Machining Allowance: Recommend 15mm per side for critical dimensions

Ultrasonic Testing: 100% volumetric inspection per AMS-STD-2154 Class A

 

Temper Designation	Process Details	Optimized Properties	Target Applications
T651	Solution heat treated, stretched (1.5-3%), artificially aged	Maximum strength	Primary aircraft structures
T7351	Solution heat treated, stretched, overaged	Improved SCC resistance, better toughness	Critical aerospace components
T7651	Solution heat treated, stretched, specially overaged	Balanced strength and SCC resistance	Wing structures

 

Heat Treatment Parameters:

Solution Heat Treatment:

Temperature: 465-480°C

Time: 1 hour per 25mm thickness (minimum)

Quench Delay: <12 seconds maximum

Artificial Aging:

T651: 120°C for 24 hours

T7351: 115°C for 6-8 hours + 175°C for 8-16 hours

Temperature Tolerance: ±2°C

 

 

 

Operation	Tool Material	Recommended Parameters	Considerations for Ultra-Thick Plate
Roughing	Carbide	Vc=300-600 m/min, fz=0.1-0.3 mm	Step-down approach, progressive depth
Finishing	PCD/CBN inserts	Vc=600-1200 m/min	Light cuts, high surface speed
Deep Hole Drilling	Carbide coolant-fed	Vc=60-120 m/min, fn=0.1-0.3 mm/rev	Peck drilling essential
Face Milling	PCD/Carbide	Vc=500-1000 m/min	Positive rake geometry

 

Manufacturing Best Practices:

Cutting Fluids: Water-soluble coolant with pH 8.5-9.5

Chip Management: High-pressure coolant for evacuation

Fixturing: Distributed clamping to minimize distortion

Cutting Strategy: Climb milling for optimal surface finish

Residual Stress Management: Rough machine, stress relieve, finish machine

 

Environment Type	Resistance Rating	Protection Method	Service Life Expectation
Industrial Atmosphere	Moderate	Anodizing + primer/topcoat	8-12 years with maintenance
Marine Environment	Poor-Fair	Anodizing + chromated primer + topcoat	5-8 years with maintenance
Stress Corrosion	Good (T7 tempers)	Overaging + surface compression	Significant improvement over T6
Exfoliation	Good (T7 tempers)	Proper heat treatment	EXCO rating of EA or better

 

Surface Treatment Options:

Anodizing:

Type II (Sulfuric): 10-25μm

Type III (Hard): 25-75μm

Chromic: 2-8μm for maximum fatigue performance

Conversion Coatings:

Chromate per MIL-DTL-5541 Class 1A

Trivalent chromium pretreatment

Paint Systems:

High-solids epoxy primer

Polyurethane topcoat

Mechanical Surface Enhancement:

Shot peening (0.008-0.012A intensity)

Laser shock peening

Property	Value	Design Significance
Density	2.81 g/cm³	Weight calculations for aircraft structures
Melting Range	477-635°C	Welding/heat treatment limitations
Thermal Conductivity	130-150 W/m·K	Heat dissipation in high-load components
Electrical Conductivity	33-40% IACS	EMI shielding applications
Specific Heat	960 J/kg·K	Thermal mass calculations
Thermal Expansion (CTE)	23.4 ×10⁻⁶/K	Thermal stress predictions
Young’s Modulus	71.7 GPa	Structural stiffness in airframe design
Poisson’s Ratio	0.33	Critical for FEA modeling

 

Special Considerations for Ultra-Thick Sections:

Residual Stress Distribution: Through-thickness mapping required

Thermal Inertia: Slow response to temperature changes

Deep Hardenability: Consistent properties through section

 

Mandatory Inspection Regime:

Chemical Composition:

Optical emission spectroscopy

Verification of all major elements and impurities

Mechanical Testing:

Full tensile test (L, LT, ST directions)

K₁c fracture toughness testing

Hardness survey (25mm grid minimum)

Non-Destructive Testing:

Ultrasonic inspection per AMS-STD-2154 Class A

Penetrant inspection of critical surfaces

Microstructural Analysis:

Grain size and morphology

Inclusion rating per ASTM E45

Certification Documentation:

Material Test Report (MTR) per EN 10204 3.1/3.2

Chemical analysis certification

Mechanical properties certification

Heat treatment chart records

NDT reports with acceptance criteria

 

 

 

Primary Aerospace Applications:

Bulkhead structures

Wing spars and carry-through structures

Landing gear components

Fuselage frames and longerons

Thick section structural members

Upper wing skins

High-load fittings

Performance Advantages for Ultra-Thick Sections:

Uniform properties throughout thickness

Superior damage tolerance

Enhanced stress corrosion resistance in T7 tempers

Improved through-thickness strength

Superior machinability in thick sections

Consistent quality through rigorous processing controls