7050 Large Diameter Aluminum Pipe

1. Material Composition & Manufacturing Process

7050 (AMS 4050M, ASTM B247) large diameter pipes feature copper-zinc-magnesium alloying system optimized for high-strength structural applications:

Alloy Chemistry:

Zinc (Zn): 5.7-6.7% (primary strengthening)
Magnesium (Mg): 1.9-2.6% (precipitation hardening)
Copper (Cu): 2.0-2.6% (stress corrosion resistance)
- Trace Elements:
Zirconium (Zr): 0.08-0.15% (grain refinement)
Iron (Fe): ≤0.15% max
Silicon (Si): ≤0.12% max
Manganese (Mn): ≤0.10% max

Advanced Manufacturing Process:

Billet Pre-heating: 430-480°C (Argon atmosphere)
Hot Extrusion: 315-410°C at 100-350 MN press force
Cold Draw Sizing: 15-30% reduction
Stretch Straightening: 1-3% permanent elongation
Heat Treatment: T7451/T7651 proprietary aging
Calibration: 3-roll planetary sizing system
Surface Finish: Micro-peening (0.5-1.2μm Ra)

Certified to AMS-QQ-A-200/11 and EN 754 standards with full digital material traceability.

2. Mechanical Properties for Heavy Structures

Property	T7451 Temper	T7651 Temper	Test Standard
Ultimate Tensile Strength	510-550 MPa	530-570 MPa	ASTM E8
Yield Strength (Rp0.2)	455-495 MPa	470-510 MPa	ASTM E8
Elongation (%)	9-12%	7-10%	ASTM E8
Fracture Toughness KIC	32 MPa√m	29 MPa√m	ASTM E399
Compression Yield	480-520 MPa	500-540 MPa	ASTM E9
Shear Strength	300-335 MPa	310-345 MPa	ASTM B565
Fatigue Strength (10⁷)	160-185 MPa	180-205 MPa	ASTM E466
Bearing Strength	840-890 MPa	860-910 MPa	ASTM E238

Maintains ≥90% mechanical properties at temperatures from -55°C to +125°C per ASTM E21.

3. Heat Treatment & Microstructural Control

Proprietary Aging Sequence:

Solution Treatment: 477°C ±5°C for 2-4 hours
Controlled Quenching: Polymer quench at 40-60°C/sec
Stress Relief: 3% stretch deformation
Aging Protocol:

T7451: 107°C/8hr + 163°C/30hr
T7651: 121°C/6hr + 177°C/20hr

Microstructural Characteristics:

Grain Size: ASTM 6-7 (25-40μm)
Precipitate Structure:

η’ (MgZn₂) phase: 10-30nm
Al₃Zr dispersoids: 5-15nm
- Dislocation Density: 4-6×10¹⁰/cm²
- Grain Boundary Structure: Discrete η-phase
- Recrystallization: ≤15%
- Texture Index: <1.5 random multiples

4. Dimensional Specifications for Large Pipes

Parameter	Standard Range	Precision Tolerance	Special Capabilities
Outer Diameter	200-1200 mm	±0.15% OD	Up to 2500 mm
Wall Thickness	8-80 mm	+10%/-5% WT	3-150 mm available
Length	3-20 m	+10mm/-0mm	Up to 30m sections
Ovality	≤0.8%	≤0.3% (critical)	–
Straightness	1.0 mm/m	0.3 mm/m	–
Perpendicularity	≤0.5°	≤0.2°	–
Wall Uniformity	±7%	±3%	–

Advanced Forming Technologies:

Spin Forming for end configurations
Flow Turning for thickness variation
Explosive Expansion for size transitions
Mandrel Forging for flanged ends
Localized Solution Heat Treatment

5. Environmental Durability Performance

Condition	Performance Rating	Key Metrics	Protection Methods
Salt Spray Exposure	Excellent	<0.002 mm/yr corrosion rate	Alodine 1200 treatment
Stress Corrosion Cracking	Good	Threshold >150 MPa	T7451 overaged temper
Galvanic Corrosion	Moderate	<0.003 mm/yr when isolated	Fiberglass isolation
Atmospheric Exposure	Excellent	0.0001 mm/yr rural environment	Chromate conversion coating
High Humidity	Good	No pitting after 3000hr	Anodizing (Type II)

Surface Enhancement Options:

Hard Anodizing (50-70μm, 500-600 HV)
Plasma Electrolytic Oxidation (PEO)
HVOF WC-Co Coating (1200-1400 HV)
Electroless Nickel Plating (ENP)
Thermal Spray Aluminum (TSA)

6. Machining & Fabrication Properties

Operation	Tool Material	Recommended Parameters	Dimensional Precision
Deep Hole Drilling	Carbide gundrills	25-45 m/min, 0.05-0.12 mm/rev	±0.05 mm
End Milling	TiAlN coated carbide	250-400 m/min, 0.1-0.3 mm/tooth	Ra 0.8-1.6μm
Tapping	Coated HSS-E taps	8-15 m/min, spiral point	6H tolerance
Boring	CBN-tipped bars	150-250 m/min, 0.05 mm/rev	IT7 grade
Trepanning	PCD cutters	60-100 m/min	Wall runout ±0.1 mm

Machinability Advantages:

Chip Formation: Short breaking chips
Built-up Edge Tendency: Low (Class B per ISO 3685)
Cutting Force Requirements: 20-30% lower than steel
Residual Stress Control: Cryogenic machining capable
Typical Surface Finish: Ra 0.4-1.6 μm achievable

7. Welding & Joining Technologies

Optimal Welding Processes:

Variable Polarity PAW (VPPAW):

Current: 180-300A
Travel Speed: 100-250 mm/min
Filler: ER7037 (Al-Zn-Mg)
- Friction Stir Welding:
Spindle Speed: 350-600 RPM
Traverse: 80-200 mm/min
Down Force: 12-20 kN

Specialized Joint Designs:

High-Strength Mechanical Joints:

Swaged collars with 1:15 taper
Interference fit bushings
1. Adhesive Bonding Systems:
Epoxy novolac: 25 MPa at 100°C
Polyurethane methacrylate: 18 MPa
1. Double-Welded Joints:
Root gap: 0.8-1.5mm
Groove angle: 60°±5°
Back-gouging: Full penetration

8. Physical Properties for Structural Applications

Property	Value	Structural Significance
Density	2.83 g/cm³	60% weight savings vs steel
Young’s Modulus	71 GPa	Stiffness-to-weight ratio
Poisson’s Ratio	0.33	Stress distribution
CTE (20-150°C)	23.6 μm/m·°C	Thermal compatibility
Thermal Conductivity	130 W/m·K	Heat dissipation
Electrical Resistivity	41.5 nΩ·m	Static discharge
Damping Capacity	0.002	Vibration reduction
Magnetic Permeability	1.00002	EMI protection

9. Testing & Certification

Rigorous Testing Protocols:

Ultrasonic Testing: 5-15 MHz probes, AWS D1.2 standards
Eddy Current Inspection: 1-3% sensitivity
Hydrostatic Testing: 1.5x design pressure
Fracture Toughness: ESIS TC24 protocol
Fatigue Testing: 10⁷ cycles minimum
Residual Stress Analysis: X-ray diffraction method

Comprehensive Certification:

NADCAP AC7108 Accreditation
ISO 9001/AS9100 Quality Systems
PED 2014/68/EU Compliance
DNV GL Type Approval
ABS Material Certification
MIL-DTL-45225 Inspection

10. Industrial Applications

Primary Application Sectors:

Aerospace structural frameworks
Missile launch tube systems
Industrial hydraulic cylinders
Energy sector gas injection pipes
Heavy machinery booms and arms
Marine propulsion shafting
High-pressure gas storage
Telescope structural components

Handling & Storage:

VCI coating with desiccant packs
Non-metallic end protectors
Wooden saddles in storage racks
Never-stack direct contact policy
ISO container transport systems