7050 aluminum alloy (AMS 4050, ASTM B247) represents an advanced aerospace-grade Al-Zn-Mg-Cu alloy engineered for superior damage tolerance and exceptional strength-to-weight ratio. The ultra-hard forged plate variant delivers optimized mechanical properties through precision thermomechanical processing:

Alloy Chemistry:

Zinc (Zn): 5.7-6.7% (primary strengthening element)

Copper (Cu): 2.0-2.6% (precipitation hardening)

Magnesium (Mg): 1.9-2.6% (strengthening precipitates)

Zirconium (Zr): 0.08-0.15% (grain structure control)

Base Material:

Aluminum (Al): ≥87.3% (balance)

Controlled Impurities:

Iron (Fe): ≤0.15% max

Silicon (Si): ≤0.12% max

Manganese (Mn): ≤0.10% max

Titanium (Ti): ≤0.06% max

Chromium (Cr): ≤0.04% max

Premium Forging Production Sequence:

Ingot Casting: Proprietary low-hydrogen, vacuum-degassed process

Homogenization: 470-490°C for 24-36 hours (computer-controlled ramp)

Surface Scalping: Minimum 10mm per surface to eliminate segregation

Pre-forging Preparation: Protective coating application

Multi-directional Forging:

Initial Deformation: 400-425°C

Intermediate Passes: 375-395°C

Final Deformation: 350-370°C

Minimum Deformation Ratio: 4:1

Post-forge Annealing: 413°C for 4-8 hours (stress equalization)

Precision Machining: Surface preparation for heat treatment

Solution Heat Treatment: 475-485°C for thickness-dependent time

Controlled Quenching: High-velocity polymer quench (>100°C/sec)

Cryogenic Treatment: Optional -75°C stabilization (24 hours)

Multi-stage Aging:

T7451: 120°C/8hr + 175°C/8hr

T7651: 120°C/6hr + 165°C/24hr

Full material traceability with digital process monitoring throughout manufacturing.

 

 

 

Property	Minimum	Typical	Test Standard	Performance Advantage
Ultimate Tensile Strength	510 MPa	540-570 MPa	ASTM E8/E8M	15% higher than 7075-T6
Yield Strength (0.2%)	455 MPa	480-510 MPa	ASTM E8/E8M	Superior aerospace loading capacity
Elongation (2 inch)	8%	10-13%	ASTM E8/E8M	Better damage tolerance than 7075
Fracture Toughness (K₁c)	30 MPa√m	33-38 MPa√m	ASTM E399	25% improvement over 7075-T6
Shear Strength	305 MPa	320-345 MPa	ASTM B769	Enhanced joint performance
Bearing Strength (e/D=2.0)	785 MPa	800-850 MPa	ASTM E238	Exceptional fastener capacity
Fatigue Strength (10⁷)	145 MPa	160-180 MPa	ASTM E466	Superior cyclic loading resistance
Hardness (Brinell)	140 HB	150-165 HB	ASTM E10	Improved wear resistance
Compressive Yield	470 MPa	490-520 MPa	ASTM E9	Critical for compression structures

 

Directionality Performance:

L/LT Tensile Strength Ratio: 1.05-1.08

L/ST Tensile Strength Ratio: 1.07-1.12

L/45° Tensile Strength Ratio: 1.02-1.06

Core-to-Surface Property Variation: <5% in thickness up to 150mm

 

 

 

Precision Thermomechanical Control:

Grain Structure Management:

Unrecrystallized, fibrous grain morphology

Controlled pancaking ratio: 5:1 to 8:1

Zr-stabilized substructure retention

Precipitate Engineering:

η’ (MgZn₂) primary strengthening

η (MgZn₂) overaging controlled

T (Al₂Mg₃Zn₃) phase distribution

S (Al₂CuMg) phase minimization

Quench Rate Control:

Critical cooling rate: >100°C/sec at surface

Core cooling rate: >60°C/sec minimum

Residual stress minimization through polymer quenchant

Multi-stage Aging Kinetics:

Nucleation stage: 120°C/6-8hr (GP zone formation)

Growth stage: 165-175°C/8-24hr (η’ precipitation)

Microstructural Characteristics:

Grain Size: ASTM 8-10 (15-30μm)

Dispersoid Size: 50-100nm (Al₃Zr)

Precipitate Density: >10^17/cm³

Recrystallized Fraction: <5% maximum

Texture: Strong brass {011}<211> component

Inclusion Rating: ≤0.3 per ASTM E45

Void Content: <0.1% volumetric

 

 

 

Parameter	Standard Range	Aerospace Tolerance	Commercial Tolerance
Thickness	20-250 mm	±0.5mm or ±1%*	±1.5mm or ±2%*
Width	1000-2500 mm	±2 mm	±5 mm
Length	2000-10000 mm	+10/-0 mm	+20/-0 mm
Flatness	N/A	0.1% of length	0.2% of length
Surface Roughness	N/A	3.2 μm Ra max	6.3 μm Ra max
Edge Straightness	N/A	1 mm per meter	3 mm per meter
Parallelism	N/A	0.5% of thickness	1.0% of thickness

*Whichever is greater

Special Processing Options:

Near Net Shape Forging: Reduced machining allowance

Contour Pre-machining: 15mm minimum stock allowance

Stress Relief: Pre-machining stress equalization

Ultrasonic Inspection: 100% volumetric testing per AMS 2154

Density: 2.83 g/cm³ (±0.02)

Weight Formula: Thickness(mm) × Width(m) × Length(m) × 2.83 = Weight(kg)

 

 

 

Temper Designation	Process Details	Optimized Properties	Target Applications
T7451	Solution heat treat, controlled stretch (1.5-3%), stress relief, overaged	Best SCC resistance with high strength	Primary aircraft structures
T7651	Solution heat treat, controlled stretch (1.5-3%), overaged (higher peak temperature)	Maximum strength with good SCC resistance	Critical load-bearing components
T7351	Solution heat treat, stress relief by stretching, specially overaged	Optimal combination of strength/fracture toughness	Fatigue-critical structures
T74	Solution heat treat, multi-stage overaging	Maximum SCC resistance	Marine/naval aerospace applications

 

Heat Treatment Parameters:

Solution Temperature: 475-485°C

Soak Time: 1 hour per 25mm thickness (minimum)

Quench Delay: <10 seconds maximum

Quench Medium: Polymer concentration 12-18%

Quench Velocity: 3-5 m/sec minimum

Aging Temperature Control: ±3°C tolerance

Post-quench Storage: <8 hours at <20°C before aging

Material Response Characteristics:

Natural Aging: Significant property changes within 48 hours

Artificial Aging: 90% of properties developed in first aging stage

Thermal Stability: Maintains >95% of properties at 100°C

Cryogenic Performance: Increased strength at subzero temperatures

Stress Relief: 2-3% permanent deformation recommended

 

 

 

Operation	Tool Material	Recommended Parameters	Special Considerations
High-Speed Milling	Premium carbide	Vc=500-1000 m/min, fz=0.1-0.25 mm	Climb milling essential
Deep Hole Drilling	Carbide coolant-fed	Vc=80-150 m/min, fn=0.15-0.35 mm/rev	Pecking cycle required
Turning	PCD/CBN inserts	Vc=600-1200 m/min	Sharp cutting edges vital
Threading	Premium HSS-E-PM	Vc=15-25 m/min	Thread rolling preferred
Reaming	Carbide reamers	Vc=40-70 m/min	H7 tolerance achievable
EDM	Copper electrodes	Low current settings	Recast layer removal required

 

Machining Optimization Strategies:

Cutting Fluids: Water-soluble coolants (pH 8.5-9.5)

Tool Coatings: TiAlN or Diamond preferred

Chip Management: High-pressure (70+ bar) coolant

Clamping Force: Moderate (avoid distortion)

Feeds/Speeds: High speed, moderate feed approach

Tool Engagement: Maximum 60% of cutter diameter

Roughing Strategy: High-efficiency machining (HEM)

Finishing: Light cuts with high surface speed

 

Environment Type	Resistance Rating	Protection Method	Performance Expectation
Industrial Atmosphere	Moderate	Anodizing + primer/topcoat	10+ years with maintenance
Marine Environment	Poor-Fair	Anodizing + chromated primer + topcoat	5-8 years with maintenance
High-Humidity	Fair	Anodizing Type II or III	3-5 years without topcoat
Chemical Exposure	Fair	Chemical conversion + sealed anodize	Application dependent
Stress Corrosion	Good (T7 tempers)	Overaging + surface compression	Significant improvement over 7075
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

Thin Film Sulfuric: 3-8μm

Tartaric-Sulfuric: 5-15μm

Conversion Coatings:

Chromate per MIL-DTL-5541 Class 1A

Trivalent chromium pretreatment

Sol-gel technology

Paint Systems:

High-solids epoxy primer

Polyurethane topcoat

Rain erosion coatings

Specialty anti-corrosion primers

Mechanical Surface Enhancement:

Shot peening (0.008-0.012A intensity)

Laser shock peening

Burnishing

 

 

 

Property	Value	Design Significance
Density	2.83 g/cm³	Weight-critical structures
Melting Range	490-630°C	Welding/heat treatment limitations
Thermal Conductivity	153-167 W/m·K	Heat dissipation capability
Electrical Conductivity	35-40% IACS	EMI shielding applications
Specific Heat	860 J/kg·K	Thermal mass calculations
Thermal Expansion (CTE)	23.5 ×10⁻⁶/K	Thermal stress prediction
Young’s Modulus	71.7 GPa	Structural stiffness
Poisson’s Ratio	0.33	Elasticity modeling
Fatigue Crack Growth Rate	da/dN = 3×10⁻⁹(ΔK)³·⁵	Damage tolerance design
Fracture Energy (G₁c)	28-32 kJ/m²	Impact resistance assessment

 

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

Eddy current testing (optional)

Microstructural Analysis:

Grain size and morphology

Recrystallization assessment

Inclusion rating per ASTM E45

Production Testing:

Heat treatment parameters verification

Quench sensitivity testing

Electrical conductivity mapping

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

Temper verification documentation

Process control parameters

Statistical process data summary

Lot traceability information

 

 

 

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

Missile structures

Structural backup hardware

Critical connection fittings

Performance Advantages vs. 7075:

10-15% higher tensile strength

20-25% improved fracture toughness

Superior stress corrosion resistance

Enhanced exfoliation corrosion resistance

Better fatigue crack growth resistance

Improved damage tolerance

Higher residual strength after impact

Better thermal stability

Superior machinability in thick sections

Enhanced through-thickness properties

 

 

 

Material Handling Protocol:

Storage Environment:

Temperature: 15-25°C

Humidity: <65% RH

Protection from precipitation

Isolation from steel products

Lifting Guidelines:

Multi-point lifting with spreader bars

Non-metallic slings