Aluminum 5083-H321
Introduction to Aluminum 5083-H321
Aluminum 5083-H321 is a strain-hardened and stabilized aluminum-magnesium-manganese alloy known for its outstanding corrosion resistance, especially in seawater and aggressive industrial environments. The H321 temper indicates that the material has been strain-hardened and stabilized to resist stress corrosion cracking and exfoliation.
Aluminum 5083-H321 is highly suitable for CNC machining of precision parts in the marine, defense, cryogenic, and transportation sectors, where long-term strength and corrosion resistance are crucial in welded or load-bearing assemblies.
Chemical, Physical, and Mechanical Properties of Aluminum 5083-H321
Chemical Composition (Typical)
Element | Composition Range (wt.%) | Key Role |
|---|---|---|
Aluminum (Al) | Balance | Base metal, provides corrosion resistance |
Magnesium (Mg) | 4.0–4.9 | Improves strength and seawater corrosion resistance |
Manganese (Mn) | 0.4–1.0 | Enhances toughness and improves fatigue strength |
Chromium (Cr) | 0.05–0.25 | Increases corrosion resistance and grain structure |
Silicon (Si) | ≤0.40 | Residual element |
Iron (Fe) | ≤0.40 | Residual element |
Copper (Cu) | ≤0.10 | Residual element |
Zinc (Zn) | ≤0.25 | Residual element |
Physical Properties
Property | Value (Typical) | Test Standard/Condition |
|---|---|---|
Density | 2.66 g/cm³ | ASTM B311 |
Melting Range | 570–640°C | ASTM E299 |
Thermal Conductivity | 121 W/m·K at 25°C | ASTM E1952 |
Electrical Conductivity | 28% 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 (H321 Temper)
Property | Value (Typical) | Test Standard |
|---|---|---|
Tensile Strength | 305–340 MPa | ASTM E8/E8M |
Yield Strength (0.2%) | 215–250 MPa | ASTM E8/E8M |
Elongation | ≥10% | ASTM E8/E8M |
Hardness | 85–95 HB | ASTM E10 |
Fatigue Strength | 110–130 MPa | ASTM E466 |
Impact Resistance | Excellent | ASTM E23 |
Key Characteristics of Aluminum 5083-H321
Superior Resistance to Marine Corrosion (ASTM G31): Designed for prolonged exposure to saltwater, Aluminum 5083-H321 forms a highly stable oxide layer and resists pitting and intergranular corrosion, even in welded structures.
Stabilized to Prevent Exfoliation and SCC: H321 temper provides excellent stress corrosion cracking resistance in thick plate and welded joints, meeting or exceeding ASTM B928 and ASTM G66 standards for marine environments.
Outstanding Weldability with Minimal Distortion: Excellent performance with 5356 filler metal for MIG/TIG welding. After welding, the alloy maintains over 90% of its strength in the heat-affected zone (HAZ).
Excellent Cryogenic Performance: Demonstrates superior ductility and toughness below -200°C, making it a suitable material for cryogenic tanks and systems.
Non-Heat Treatable Alloy with Stable Dimensional Control: Strength is achieved through cold working and stabilization rather than heat treatment, providing consistency across large-scale machined components.
CNC Machining Challenges and Solutions for Aluminum 5083-H321
Machining Challenges
Work Hardening Behavior: Can lead to excessive burrs and tool wear if cut aggressively without sharp tools.
Adhesive Material Characteristics: May stick to tool edges under high heat or poor chip evacuation.
Chip Control for Long Sections: Commonly machined from large plates requiring chip breakers and coolant optimization.
Optimized Machining Strategies
Tool Selection
Parameter | Recommendation | Rationale |
|---|---|---|
Tool Material | TiAlN-coated carbide or PCD tools | Reduces sticking and wear under prolonged cuts |
Geometry | Large rake angle, chipbreakers | Promotes surface finish and effective chip removal |
Cutting Speed | 200–350 m/min | Prevents thermal damage and tool softening |
Feed Rate | 0.10–0.30 mm/rev | Balances surface finish and throughput |
Coolant | Flood or high-pressure (30–50 bar) | Maintains surface quality and dimensional accuracy |
Aluminum 5083-H321 Cutting Parameters (ISO 513 Compliance)
Operation | Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) | Coolant Pressure (bar) |
|---|---|---|---|---|
Roughing | 200–280 | 0.20–0.30 | 2.0–3.5 | 30–50 (Flood) |
Finishing | 280–350 | 0.05–0.10 | 0.2–1.0 | 40–60 (Flood/Mist) |
Surface Treatment for Aluminum 5083-H321 CNC Parts
Anodizing: Type II anodizing provides 10–25 µm decorative protection; hard anodizing adds up to 50 µm for wear resistance.
Powder Coating: 60–100 µm thick polyester or epoxy coatings for marine or architectural use.
Electropolishing: Enhances fatigue resistance and improves corrosion behavior of load-bearing parts.
Passivation: Used in combination with anodizing or alodine to improve pre-treatment cleanliness.
Brushing: Provides Ra 1.0–1.6 µm matte finishes ideal for aesthetic panels or exposed frames.
Alodine Coating: MIL-DTL-5541-compliant chromate conversion for electronic enclosures and painted parts.
UV Coating: Protects marine and outdoor parts from fading, discoloration, and weathering.
Lacquer Coating: Adds aesthetic gloss and enhances chemical resistance for display-grade parts.
Industry Applications of Aluminum 5083-H321
Marine: CNC-machined hull structures, bulkheads, deck panels, and ballast tanks require seawater resistance and welded integrity.
Defense: Vehicle armor, naval enclosures, and radar housings where high strength and weldability are required.
Cryogenic Systems: LNG tank components, piping flanges, and support systems operating below -150°C.
Transportation: Lightweight trailer bodies, battery enclosures, and undercarriage systems for trucks and railcars.
Industrial Equipment: CNC-machined parts exposed to acids, chemicals, or humid environments, including HVAC shells and pressure housings.
FAQs
How does Aluminum 5083-H321 differ from H116 or H111 in corrosion performance?
What filler metal is recommended for welding Aluminum 5083-H321 parts?
What is the typical dimensional stability of CNC machined 5083-H321 after welding?
Can 5083-H321 be anodized or powder coated for marine applications?
What are the best machining practices to avoid work hardening in 5083-H321?
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