7075-T6 Aluminum Round Bar

1. Material Composition & Manufacturing Process

7075-T6 aluminum round bar represents the pinnacle of high-strength aluminum alloys, offering an exceptional combination of strength, hardness, and stress resistance for aerospace, defense, and high-performance mechanical 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 Manufacturing Process:

1. Melt Preparation:
   1. Primary high-purity aluminum (99.7% minimum)
   1. Precise alloying element additions with ±0.1% tolerance
   1. Advanced filtration through ceramic foam filters (30-40 ppi)
   1. SNIF degassing treatment (hydrogen < 0.10 ml/100g)
   1. Grain refinement with Al-Ti-B master alloy
   1. Direct-chill (DC) semi-continuous casting
2. Homogenization:
   1. 460-480°C for 24-48 hours
   1. Uniform temperature control: ±5°C
   1. Controlled cooling rate: 20-30°C/hour
   1. Dissolution of coarse intermetallics
   1. Microsegregation elimination
3. Hot Working Process:
   1. Breakdown forging/rolling: 385-415°C
   1. Intermediate operations: 370-400°C
   1. Final hot working: 350-380°C
   1. Computerized temperature monitoring throughout
4. Solution Heat Treatment:
   1. 465-485°C for 1-2 hours (diameter dependent)
   1. Temperature uniformity: ±3°C
   1. Rapid transfer to quenching medium
   1. Maximum transfer time: 10 seconds
5. Quenching:
   1. Cold water (10-30°C)
   1. Agitation for uniform cooling
   1. Minimum cooling rate: 100°C/sec at surface
6. Cold Stretching (T651):
   1. 1.5-3.0% permanent deformation
   1. Stress relief and straightening
   1. Dimensional accuracy enhancement
7. Artificial Aging (T6):
   1. Dual-stage aging process:
      1. First stage: 110-130°C for 4-6 hours
      1. Second stage: 165-175°C for 8-12 hours
   1. Temperature uniformity: ±3°C
   1. Controlled cooling after aging
8. Final Processing:
   1. Precision centerless grinding (optional)
   1. Stress-free straightening
   1. Nondestructive testing
   1. Surface treatment and protection

Full process traceability with computerized quality monitoring at all stages.

2. Mechanical Properties of 7075-T6 Aluminum Round Bar

Property	Minimum	Typical Range	Test Method
Ultimate Tensile Strength	570 MPa	580-600 MPa	ASTM E8
Yield Strength (0.2%)	500 MPa	510-540 MPa	ASTM E8
Elongation (2 inch)	7%	8-11%	ASTM E8
Hardness (Brinell)	150 HB	155-165 HB	ASTM E10
Fatigue Strength (5×10⁸)	160 MPa	170-190 MPa	ASTM E466
Shear Strength	330 MPa	340-360 MPa	ASTM B769
Fracture Toughness (K₁c)	24 MPa√m	25-29 MPa√m	ASTM E399
Compressive Yield Strength	520 MPa	530-550 MPa	ASTM E9
Modulus of Elasticity	71.7 GPa	71.7-72.4 GPa	ASTM E111

Property Distribution:

• Longitudinal to transverse property ratio: 1.00:0.95 (strength), 1.00:0.75 (elongation)
• Variation across diameter: <5% for diameters up to 75mm, <8% for diameters >75mm
• Core to surface hardness variation: <10 HB for diameters up to 100mm
• Property stability: <3% strength reduction after 10,000 hours at 100°C
• Stress Corrosion Cracking Threshold: 125-175 MPa (dependent on environment)

3. Microstructural Characteristics

Key Microstructural Features:

1. Grain Structure:
   1. Partially recrystallized structure with elongated grains
   1. ASTM grain size 7-9 (32-16μm)
   1. Aspect ratio: 2:1 to 4:1 (length:width)
   1. Well-controlled grain flow pattern
2. Precipitate Distribution:
   1. MgZn₂ (η/η’) strengthening precipitates: 5-15nm
   1. CuMgAl₂ (S-phase) precipitates
   1. Al₇Cu₂Fe intermetallics: Controlled size and distribution
   1. Al₁₂Mg₂Cr dispersoids: 50-200nm
3. Texture Development:
   1. Strong <111> and <100> fiber textures
   1. Texture intensity: 3-8× random
   1. Optimized for maximum strength in primary loading directions
4. Special Features:
   1. Precipitation-hardened microstructure
   1. Minimal precipitate-free zones (PFZs) at grain boundaries
   1. Controlled distribution of coarse intermetallics
   1. Fine dispersoid distribution for recrystallization control

4. Dimensional Specifications & Tolerances

Parameter	Standard Range	Precision Tolerance	Commercial Tolerance	Test Method
Diameter	10-250 mm	±0.10mm up to 30mm	±0.20mm up to 30mm	Micrometer
		±0.4% above 30mm	±0.7% above 30mm
Ovality	N/A	50% of diameter tolerance	75% of diameter tolerance	Micrometer
Length	2000-6000 mm	±2mm	±5mm	Tape measure
Straightness	N/A	0.2mm/m	0.5mm/m	Straightedge
Surface Roughness	N/A	1.6 μm Ra max	3.2 μm Ra max	Profilometer
Cut End Squareness	N/A	0.5° max	1.0° max	Protractor

Standard Available Forms:

• Diameters: 10mm to 250mm (larger sizes available on request)
• Standard Lengths: 2000mm, 3000mm, 4000mm, 6000mm
• Custom cut lengths available
• Centerless ground bars available for precision applications
• Saw-cut ends with protective end caps

5. Temper Designations & Heat Treatment Options

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 aerospace components	Improved stress corrosion resistance
T73	Overaged for stress corrosion resistance	Corrosion-critical applications	Better SCC resistance with reduced strength
T76	Modified overaging treatment	Balanced properties	Compromise between T6 and T73
T7351	T73 + stress relieved by stretching	Thick sections with residual stress concerns	Dimensional stability with SCC resistance

Temper Selection Guidance:

• T6/T651: Highest strength requirements
• T73/T7351: Stress-corrosion critical applications
• T76: Balanced properties for general aerospace applications

6. Machining & Fabrication Characteristics

Operation	Tool Material	Recommended Parameters	Comments
Turning	Carbide, PCD	Vc=150-300 m/min, f=0.1-0.3 mm/rev	Sharp tools essential
Drilling	HSS-Co, Carbide	Vc=60-120 m/min, f=0.15-0.35 mm/rev	Frequent chip clearing
Milling	Carbide, PCD	Vc=180-350 m/min, fz=0.05-0.15 mm	Climb milling preferred
Tapping	HSS-Co, TiN coated	Vc=10-20 m/min	Thread quality sensitive to heat
Reaming	Carbide, PCD	Vc=40-90 m/min, f=0.1-0.3 mm/rev	H7 tolerance achievable
Thread Milling	Carbide	Vc=100-200 m/min, fz=0.03-0.08 mm	Preferred over tapping for critical threads

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 preferred (8-10% concentration)
• Tool Wear: Moderate with proper parameters
• Cutting Forces: Higher than other aluminum alloys
• Weldability: Poor (not recommended for structural applications)
• Cold Working: Limited formability
• Hot Working: Not recommended in T6 condition
• Heat Treatment: Can be fully re-heat treated after machining

7. Corrosion Resistance & Protection Systems

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	Proper temper + protection	Critical in 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 available
• Mechanical Protection:
  • Shot peening for enhanced fatigue and SCC resistance
  • Glass bead blasting for uniform appearance

8. Physical Properties for Engineering Design

Property	Value	Design Consideration
Density	2.81 g/cm³	Weight calculation for components
Melting Range	477-635°C	Heat treatment limitations
Thermal Conductivity	130-150 W/m·K	Thermal management design
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
Magnetic Permeability	~1.00 (non-magnetic)	Electronic applications

Design Considerations:

• Operating Temperature Range: -70°C to +120°C
• Property Retention: Excellent below 100°C, gradual degradation above
• Stress Relaxation: Minimal below 100°C
• Fatigue Life: Superior to most aluminum alloys
• Notch Sensitivity: Moderate to high
• Cryogenic Performance: Good strength retention at low temperatures
• Vibration Damping: Poor (typical of high-strength aluminum)

9. Quality Assurance & Testing

Standard Testing Procedures:

1. Chemical Composition:
   1. Optical emission spectroscopy
   1. X-ray fluorescence analysis
   1. Verification of all major elements and impurities
2. Mechanical Testing:
   1. Tensile testing (longitudinal and transverse)
   1. Hardness testing (Brinell, Rockwell B)
   1. Impact testing (when required)
   1. Fatigue testing (for critical applications)
3. Dimensional Inspection:
   1. Diameter/ovality at multiple locations
   1. Straightness verification
   1. Length measurement
4. Nondestructive Testing:
   1. Ultrasonic inspection per AMS-STD-2154
   1. Eddy current testing for surface defects
   1. Penetrant inspection (critical applications)
5. Microstructural Analysis:
   1. Grain size determination
   1. Intermetallic particle evaluation
   1. Exfoliation corrosion susceptibility (ASTM G34)

Standard Certifications:

• Mill Test Report (EN 10204 3.1)
• Chemical analysis certification
• Mechanical properties certification
• Heat treatment certification
• Nondestructive testing certification
• Material traceability documentation

10. Applications & Design Considerations

Primary Applications:

• Aerospace Components:
  • Aircraft landing gear components
  • Wing spars and structural elements
  • Fuselage frames and bulkheads
  • Engine mounts and supports
• Defense Applications:
  • Missile components
  • Weapons systems parts
  • Armored vehicle components
  • Tactical equipment fixtures
• High-Performance Automotive:
  • Drive shafts
  • Suspension components
  • Connecting rods
  • Performance-critical fasteners
• Industrial Equipment:
  • High-stress machine parts
  • Molds for plastic injection
  • Hydraulic system components
  • Robotics and automation components
• Specialized Applications:
  • Precision instrument components
  • High-performance sporting equipment
  • Rock climbing equipment
  • Camera mounting systems

Design Advantages:

• Exceptional strength-to-weight ratio
• Superior fatigue performance
• High resistance to mechanical wear
• Excellent machining characteristics
• Dimensional stability after machining
• Reliable performance in high-stress applications
• Comprehensive material database for engineering design
• Wide availability in standard sizes