Magnesium EQ-21A-T6,UNS M18330; ,E FOUR

### **Technical Datasheet: Magnesium Alloy EQ21A-T6, UNS M18330** --- #### **1. Material Overview** EQ21A-T6 is an advanced magnesium alloy with rare earth elements and silver additions, supplied in the solution heat-treated and artificially aged condition. As an improved version of the EQ21 alloy, it offers enhanced mechanical properties, better corrosion resistance, and improved high-temperature stability, making it suitable for the most demanding aerospace and racing applications. --- #### **2. Key Features** - **Enhanced high-temperature strength** and creep resistance - **Superior corrosion resistance** compared to standard EQ21 - **Excellent castability** with reduced porosity - **Improved fatigue performance** - **Good weldability** and repairability - **Outstanding mechanical properties** retention at elevated temperatures --- #### **3. Chemical Composition (Weight %)** | Element | Composition (%) | |---------|-----------------| | **Rare Earths (RE)** | 2.0–2.7% | | **Silver (Ag)** | 2.0–2.7% | | **Zirconium (Zr)** | 0.5–1.0% | | **Zinc (Zn)** | 0.1–0.5% | | **Manganese (Mn)** | ≤ 0.10% | | **Silicon (Si)** | ≤ 0.05% | | **Copper (Cu)** | ≤ 0.03% | | **Iron (Fe)** | ≤ 0.008% | | **Nickel (Ni)** | ≤ 0.003% | | **Other Elements** | ≤ 0.20% | | **Magnesium (Mg)** | Balance | *Note: The optimized chemical composition with tighter impurity control provides improved corrosion resistance and more consistent mechanical properties compared to standard EQ21.* --- #### **4. Mechanical Properties (T6 Temper)** | Property | Room Temperature | 200°C (392°F) | 250°C (482°F) | |----------|------------------|---------------|---------------| | **Ultimate Tensile Strength** | 300–340 MPa | 240–270 MPa | 200–230 MPa | | **Tensile Yield Strength (0.2%)** | 220–260 MPa | 190–220 MPa | 160–190 MPa | | **Elongation (% in 50mm)** | 6–12% | 10–16% | 12–20% | | **Compressive Yield Strength** | 220–260 MPa | 190–220 MPa | 160–190 MPa | | **Hardness (Brinell)** | 85–100 HB | 70–80 HB | 60–70 HB | | **Shear Strength** | 170–200 MPa | 140–160 MPa | 120–140 MPa | | **Fatigue Strength** | 140–160 MPa | 110–130 MPa | 90–110 MPa | --- #### **5. Physical Properties** | Property | Value | |----------|-------| | **Density** | 1.83 g/cm³ | | **Melting Range** | 545–635°C | | **Specific Heat** | 1.01 kJ/kg·K | | **Thermal Conductivity** | 108 W/m·K | | **Coefficient of Thermal Expansion** | 26.3 μm/m·K | | **Modulus of Elasticity** | 44.5 GPa | | **Poisson's Ratio** | 0.35 | --- #### **6. Heat Treatment Cycle (T6)** - **Solution Treatment:** 530°C ± 5°C for 8–10 hours - **Quenching:** Hot water (75–95°C) - **Artificial Aging:** 205°C ± 5°C for 16–20 hours - **Cooling:** Controlled air cooling - **Microstructure:** Refined grain structure with optimized precipitate distribution --- #### **7. Applicable Standards** - **ASTM International:** - **ASTM B80** – Standard Specification for Magnesium-Alloy Sand Castings - **ASTM B199** – Standard Specification for Magnesium-Alloy Permanent Mold Castings - **Aerospace Standards:** - **AMS 4433** – Magnesium Alloy Castings, Sand (EQ21A) - **BAC 5731** – Boeing Material Specification - **European Standards:** - **EN 1753** – Magnesium and magnesium alloys - **Unified Numbering System:** - **UNS M18330** - **Aerospace OEM Specifications:** - Airbus, Boeing, and other major aerospace manufacturers --- #### **8. Manufacturing Characteristics** - **Casting Methods:** Sand casting, permanent mold casting, investment casting - **Optimal Pouring Temperature:** 725–775°C - **Fluidity:** Excellent - **Hot Tearing Resistance:** Very good - **Machinability:** Very good (sharp tools with adequate cooling) - **Weldability:** Good (TIG welding with compatible filler wire) --- #### **9. Applications** - **Aerospace:** - Jet engine components (compressor casings, housings) - Helicopter transmission systems - Aircraft accessory gearboxes - Spacecraft components - Missile and rocket parts - **High-Performance Automotive:** - Turbocharger housings and components - High-performance engine blocks - Racing transmission cases - High-stress suspension components - **Defense and Military:** - Armored vehicle components - Portable weapon systems - Military aircraft structures - **Industrial:** - High-temperature pump components - Compressor parts for high-performance applications - Specialized machinery operating at elevated temperatures --- #### **10. Corrosion Performance & Protection** - **Salt Spray Resistance:** >1200 hours to initial corrosion (ASTM B117) - **Galvanic Corrosion:** Requires isolation from more noble metals - **High-Temperature Oxidation:** Excellent resistance up to 400°C - **Stress Corrosion Cracking:** Excellent resistance - **Recommended Coatings:** High-temperature conversion coatings, anodizing, specialized paint systems --- #### **11. Design Guidelines** - **Maximum Service Temperature:** 300°C continuous, 350°C short-term exposure - **Recommended Section Thickness:** 4–100 mm - **Thermal Considerations:** Account for thermal expansion in high-temperature designs - **Fatigue Design:** Excellent for high-cycle fatigue applications - **Quality Assurance:** Requires comprehensive NDT for critical applications --- #### **12. Comparison with Similar Alloys** - **vs. EQ21-T6:** Improved mechanical properties and corrosion resistance - **vs. WE43-T6:** Better castability and higher strength at elevated temperatures - **vs. QE22A-T6:** Enhanced high-temperature performance and corrosion resistance - **vs. Conventional Mg Alloys:** Significantly superior in all aspects --- **Note:** EQ21A-T6 represents the premium category of high-performance magnesium alloys, offering exceptional properties for critical applications in aerospace, defense, and high-performance automotive industries. The improved chemistry and optimized heat treatment provide more consistent properties and enhanced performance compared to earlier generations. For critical applications, always consult with materials engineering specialists and conduct comprehensive testing and qualification programs.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3331 gallon liquid totes Special package is available on request.