Forged 7075 T6 Aluminum Alloy Pipe

1. Material Composition & Forging Process

Forged 7075-T6 pipes conform to AMS 4148, ASTM B247, and ASME SB247 standards, featuring optimized zinc-copper-magnesium composition for ultra-high strength applications:

• Alloy Composition:

• Zinc (Zn): 5.1-6.1% (primary strengthening element)
• Magnesium (Mg): 2.1-2.9% (forms MgZn₂ precipitates)
• Copper (Cu): 1.2-2.0% (enhances stress corrosion resistance)
  • Base Material:
• Aluminum (Al): ≥88.0% (balance)
  • Trace Elements:
• Chromium (Cr): 0.18-0.40% (grain refinement)
• Iron (Fe): ≤0.50% max
• Silicon (Si): ≤0.40% max

Forging Process Specifications:

• Preform heating: 370-420°C
• Forging temperature: 340-380°C
• Reduction ratio: 4:1 to 6:1 minimum
• Grain flow orientation: Longitudinal alignment (±10°)
• Press capacity: 10,000-50,000 ton hydraulic
• Forging strain rate: 0.5-5 sec⁻¹

Third-party verification per NADCAP AC7101 confirms homogeneity with <3% elemental deviation. Complies with MIL-F-7216 for aerospace applications and ISO 6363-2 for extruded precision tubes.

2. Strength Performance

Forged 7075-T6 demonstrates superior mechanical properties compared to standard extrusions:

Property	Forged Pipe	Standard Extrusion	Test Standard
Ultimate Tensile Strength	560-580 MPa	525-550 MPa	ASTM E8/E21
Yield Strength (Rp0.2)	490-510 MPa	460-480 MPa	ASTM E8/E21
Elongation at Break (%)	8-12%	5-9%	ASTM E8/E21
Fracture Toughness	36 MPa√m	28-32 MPa√m	ASTM E399
Shear Strength	325 MPa	300 MPa	ASTM B769
Fatigue Strength (10⁷)	160-180 MPa	140-155 MPa	ISO 1099
Stress Rupture (100hr/150°C)	260 MPa	220 MPa	ASTM E139
Compression Strength	540 MPa	500 MPa	ASTM E9

Improved directional properties provide 12-15% higher transverse strength and superior damage tolerance under cyclic loading.

3. Heat Treatment Process

Specialized T6 treatment sequence for forged components:

Solution Treatment:

• 465-485°C (±5°C) for 2-3 hours
• Controlled atmosphere: Argon gas blanketing

 

Rapid Quench:

• Polyalkylene glycol solution (30% concentration)
• Quench speed: >200°C/sec core cooling
• Agitation: 1.0-1.5 m/sec flow velocity

Stress Relief:

• Cryogenic treatment at -70°C for 2 hours

Artificial Aging:

• 120-125°C for 24 hours + 165-170°C for 8 hours
• Double-stage aging for optimized η’ phase precipitation

Microstructural Features:

• Grain size: ASTM 7-8 (15-30μm)
• Precipitate density: 10¹⁷/m³ η’ phase (MgZn₂)
• Forging texture intensity: 4.5-5.5 multiples random
• Inclusion rating: A0.5/B0.5 per ASTM E45
• Recrystallization: <10%

4. Dimensions & Customization

Precision-forged pipe specifications:

Parameter	Standard Range	Precision Grade	Custom Options
Outer Diameter	25-600 mm	±0.05% OD	Oval/hex profiles
Wall Thickness	3-50 mm	±5% WT	Tapered walls
Length	1-12 m	+0/-1.5 mm	Up to 20m
Straightness	–	0.25 mm/m	±0.1 mm/m
Wall Concentricity	≤0.5% TIR	≤0.2% TIR	≤0.1% TIR
Surface Roughness	Ra 1.6μm	Ra 0.4μm	Mirror finish

Advanced Fabrication:

• Radial forging for seamless reduction
• Rotary piercing for hollow blooms
• Mandrel-assisted forging for thin walls
• Isothermal forging for complex geometries
• Flow forming for high-precision bores
• Pilger milling for nuclear applications

5. Corrosion Resistance Properties

Environmental Performance Data

Environment	Forged 7075-T6 Rating	Corrosion Rate (μm/yr)	Protection Systems
Marine Atmosphere	Fair	25-40 μm/yr	HVOF WC-17Co coating
Industrial SO₂	Poor	100-150 μm/yr	Electroplated Ni-Cd
Stress Corrosion	Moderate	SCC threshold 150MPa	Shot peening + anodizing
Alclad 7075	Excellent	<1 μm/yr	5% clad layer
Forged vs Wrought	+30% SCC resistance	–	Optimized grain boundaries

Protection Technologies:

• Plasma Electrolytic Oxidation (PEO):

• Thickness: 50-100μm
• Hardness: >1500 HV
  • Ion Vapor Deposition (IVD):
• Aluminum coating: 20-50μm
• Salt spray resistance: >3000hrs
  • Electroless Nickel:
• Ni-P (9-12%): 25-75μm
• Phosphorous content control

6. Machinability Characteristics

Specialized Machining Parameters

Operation	Tooling	Speed (m/min)	Feed (mm/rev)	Notes
Turning	PCD inserts	800-1200	0.1-0.25	7° positive rake
Drilling	Coated carbide (TiAlN)	50-80	0.03-0.08	135° split point
Milling	SiAlN ceramic inserts	400-600	0.05-0.12	Trochoidal paths
Threading	TiCN coated taps	10-15	Pitch matched	75% thread depth
Boring	Cubic boron nitride	200-350	0.04-0.10	Dampened bars

Machining Performance:

• Machinability index: 50% (baseline: 6061-T6=100%)
• Tool life improvement: 200% with cryogenic cooling
• Surface finish: Ra 0.2μm achievable
• Chatter resistance: +40% vs extruded pipes
• Residual stress control: Post-machining stabilization at 120°C
• Chip formation: Segmented chips requiring power-thru toolholders

7. Weldability & Joining Methods

Requires specialized joining techniques due to heat-affected zone (HAZ) sensitivity:

Friction Welding Preferred:

• Inertia drive welding parameters:

• RPM: 2500-5000
• Axial pressure: 250-400 MPa
• Burn-off length: 2-6mm
• Upset force: 400-700 MPa
  • Dissimilar welding compatibility:
• To titanium: ER4043 filler
• To steel: Explosive welding transition joints

Alternative Joining:

1. Adhesive Bonding:

• Epoxy-novolac systems: 45 MPa shear
• Surface prep: Piranha etch solution
  2. Mechanical Fastening:
• Hi-Lok pins: 220-260 ksi strength
• Lock bolts: Vibration resistant to 50g
  3. Diffusion Bonding:
• Temperature: 510-530°C
• Pressure: 10-15 MPa
• Time: 60-90 minutes

8. Physical Properties

Property	Value	Test Standard
Density	2.81 g/cm³	ASTM B311
Thermal Conductivity (25°C)	130 W/m·K	ASTM E1461
CTE (20-100°C)	23.6 μm/m·°C	ASTM E228
Electrical Conductivity	33% IACS	ASTM B193
Modulus of Elasticity	71.0 GPa	ASTM E111
Specific Heat (200°C)	1050 J/kg·K	ASTM E1269
Thermal Diffusivity	55 mm²/s	ASTM E1461
Solidus Temperature	477°C	ASTM E228
Magnetic Permeability	1.00002	ASTM A342

9. Surface Quality Standards

• Surface integrity requirements (AMS 2772):

• No forging laps or cold shuts
• Surface discontinuities: ≤0.1mm depth
• Tool marks: ≤0.01mm height
• Heat tint control: Max ΔE=1.0
  • Finishing processes:
• Chemical milling: 0.05-0.5mm stock removal
• Electropolishing: 20-100μm removal
• Vibratory finishing: Surface compression
  • Inspection methods:
• Fluorescent penetrant: Level 3 sensitivity
• White light interferometry: 0.1μm resolution
• Barkhausen noise analysis for residual stress

10. Certifications & Testing

Quality Assurance Protocols

• Material Verification:

• Optical emission spectrometry
• Ultrasonic spectroscopy for inclusions
  • Mechanical Testing:
• Through-thickness tensile tests
• Charpy V-notch at -40°C (>15J required)
• Creep testing to 10,000 hours
  • NDE Requirements:
• Phased array UT: 10MHz probes
• Digital radiography: ASTM E2662 compliance
• Thermographic inspection: 5μm resolution

Industry Certifications

• AS9100 Aerospace Quality Management
• NADCAP AC7117 for forgings
• PED 2014/68/EU Category IV
• NORSOK M650 for offshore systems
• ITAR compliance for defense
• ABS Type Approval for marine systems

Primary Applications: Aircraft landing gear components, missile launch tubes, racing suspension systems, helicopter drive shafts, high-pressure hydraulic cylinders, and structural components requiring superior strength-to-weight ratio.

Delivery Specifications: Vacuum-sealed desiccated packaging, wooden crates with anti-vibration suspension. Standard lead time: 12-16 weeks.