Aluminum 5086
Introduction to Aluminum 5086
Aluminum 5086 is a high-strength, non-heat-treatable aluminum-magnesium alloy offering superior corrosion resistance, especially in marine and saltwater environments. It maintains excellent weldability and moderate strength after welding, making it an ideal choice for structural applications requiring resistance to harsh environmental conditions.
Thanks to its balanced mechanical performance and durability, Aluminum 5086 is widely used in CNC machining for components in marine, defense, automotive, and transportation industries that demand long-term reliability and corrosion protection.
Chemical, Physical, and Mechanical Properties of Aluminum 5086
Chemical Composition (Typical)
Element | Composition Range (wt.%) | Key Role |
|---|---|---|
Aluminum (Al) | Balance | Base element with excellent corrosion resistance |
Magnesium (Mg) | 3.5–4.5 | Enhances strength and corrosion resistance |
Manganese (Mn) | 0.2–0.7 | Improves strength and toughness |
Iron (Fe) | ≤0.5 | Residual element |
Silicon (Si) | ≤0.4 | Residual element |
Chromium (Cr) | 0.05–0.25 | Improves corrosion resistance in seawater |
Copper (Cu) | ≤0.1 | Maintains corrosion performance |
Zinc (Zn) | ≤0.25 | Residual element |
Physical Properties
Property | Value (Typical) | Test Standard/Condition |
|---|---|---|
Density | 2.66 g/cm³ | ASTM B311 |
Melting Point | 590–640°C | ASTM E299 |
Thermal Conductivity | 121 W/m·K at 25°C | ASTM E1952 |
Electrical Conductivity | 32% IACS at 20°C | ASTM B193 |
Coefficient of Expansion | 25.3 µm/m·°C | ASTM E228 |
Specific Heat Capacity | 900 J/kg·K | ASTM E1269 |
Elastic Modulus | 70 GPa | ASTM E111 |
Mechanical Properties (H116 Temper)
Property | Value (Typical) | Test Standard |
|---|---|---|
Tensile Strength | 290–345 MPa | ASTM E8/E8M |
Yield Strength (0.2%) | 210–240 MPa | ASTM E8/E8M |
Elongation | ≥10% | ASTM E8/E8M |
Hardness | 85 HB | ASTM E10 |
Fatigue Strength | 110 MPa | ASTM E466 |
Impact Resistance | Excellent | ASTM E23 |
Key Characteristics of Aluminum 5086
Marine-Grade Corrosion Resistance: Aluminum 5086 resists corrosion in seawater and brine environments, outperforming other 5xxx series alloys due to its chromium and magnesium content. It’s ideal for coastal and underwater applications.
Weldability with Strength Retention: Maintains mechanical strength post-welding, unlike many other alloys. Compatible with 5356 filler metal for MIG/TIG processes with low distortion and excellent fatigue life.
High Strength and Impact Resistance: Offers a good balance of tensile strength and ductility—suitable for armor plating, hull structures, and shock-resistant components.
Cold Work Hardening Capability: Strength can be improved via strain hardening to H116 or H32 tempers without sacrificing corrosion resistance.
Non-Heat Treatable with Dimensional Stability: Unlike 6xxx or 7xxx series, properties are stable under heat exposure, making it well-suited for CNC machining of large or load-bearing structures.
CNC Machining Challenges and Solutions for Aluminum 5086
Machining Challenges
Tougher than 6061 or 5052: Requires slower feeds and appropriate tooling to maintain finish quality.
Tendency to Gall: Material adhesion to cutting tools can occur without proper tool coatings and lubrication.
Surface Work Hardening: Can result in tool chatter or dimensional inaccuracies if re-cut.
Optimized Machining Strategies
Tool Selection
Parameter | Recommendation | Rationale |
|---|---|---|
Tool Material | TiB₂- or TiAlN-coated carbide tools | Prevents built-up edge and resists abrasion |
Geometry | Positive rake with high-polish edge | Improves chip flow and reduces heat generation |
Cutting Speed | 180–300 m/min | Balances thermal load and surface integrity |
Feed Rate | 0.10–0.25 mm/rev | Maintains tolerance and avoids chatter |
Coolant | Flood or high-pressure mist | Controls temperature and chip evacuation |
Aluminum 5086 Cutting Parameters (ISO 513 Compliance)
Operation | Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) | Coolant Pressure (bar) |
|---|---|---|---|---|
Roughing | 180–240 | 0.15–0.25 | 2.0–4.0 | 25–35 (Flood) |
Finishing | 240–300 | 0.05–0.15 | 0.2–1.0 | 35–50 (Flood/Mist) |
Surface Treatment for Aluminum 5086 CNC Parts
Anodizing: Accepts Type II and hard coat anodizing. Provides wear resistance and oxide thickness of up to 50 µm.
Powder Coating: 60–120 µm coatings offer salt spray resistance for over 1000 hours in ASTM B117 tests.
Electropolishing: Enhances corrosion resistance and appearance, especially for parts exposed to salt fog.
Passivation: Typically used before coating to clean and stabilize the surface.
Brushing: Ra 0.8–1.6 µm satin finishes improve the appearance and surface cleanliness.
Alodine Coating: MIL-DTL-5541-compliant chromate conversion adds anti-corrosion properties while maintaining conductivity.
UV Coating: Adds a 5–15 µm film for added scratch and moisture protection.
Lacquer Coating: Transparent finish enhances aesthetics and resists salt spray degradation.
Industry Applications of Aluminum 5086
Marine: Hull plates, deck structures, and underwater brackets require corrosion resistance and strength.
Defense: Armor panels, blast-resistant enclosures, and structural supports for land and sea vehicles.
Automotive: Truck trailers, tankers, and suspension parts exposed to road salts and moisture.
Rail and Transport: Welded railcar tanks, engine frames, and lightweight structural members.
Energy and Oil & Gas: Piping supports, submersible housings, and load-bearing frames for corrosive environments.
FAQs
What are the advantages of Aluminum 5086 over 5052 and 6061 for marine use?
How does Aluminum 5086 perform in welded CNC assemblies?
What surface treatments enhance corrosion resistance for Aluminum 5086 parts?
What machining tolerances can be achieved with CNC 5086 parts?
Is Aluminum 5086 suitable for armor plating and military-grade components?
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