Magnesium HK31A-H24，UNS M13310;,E FOUR

Product Introduction: Magnesium Alloy HK31A-H24 (UNS M13310)** **Magnesium Alloy HK31A-H24** is a high-strength, heat-resistant magnesium alloy supplied in a strain-hardened and partially annealed temper. It is specifically engineered for applications requiring a superior strength-to-weight ratio at elevated temperatures, maintaining useful mechanical properties up to approximately 315°C (600°F). The **H24 temper** indicates the material has been strain-hardened and then partially annealed, resulting in a stable condition with an optimal balance of strength and formability for many aerospace and engineering applications. This alloy is part of the "H" series of magnesium alloys, which are strengthened with thorium and zirconium for enhanced high-temperature performance. --- #### **1. Chemical Composition** The chemical composition conforms to strict international standards, as outlined below. | Element | Composition (%) | | :--- | :--- | | **Magnesium (Mg)** | Balance | | **Thorium (Th)** | 2.5 - 4.0 | | **Zirconium (Zr)** | 0.45 - 1.0 (Min. 0.45) | | **Zinc (Zn)** | ≤ 0.30 | | **Manganese (Mn)** | ≤ 0.15 | | **Silicon (Si)** | ≤ 0.01 | | **Copper (Cu)** | ≤ 0.10 | | **Nickel (Ni)** | ≤ 0.01 | | **Iron (Fe)** | ≤ 0.05 | | **Other Impurities** | ≤ 0.30 (each) | **Key Role of Alloying Elements:** * **Thorium (Th):** The primary strengthening element. It forms stable intermetallic precipitates (e.g., Mg₂₃Th₆) that provide exceptional creep resistance and strength retention at high temperatures. * **Zirconium (Zr):** Acts as a potent grain refiner during casting and working, which significantly enhances the alloy's strength, ductility, and uniformity. --- #### **2. Physical Properties** The following table outlines the key physical properties of Magnesium HK31A alloy. | Property | Value | | :--- | :--- | | **Density** | 1.79 g/cm³ (0.065 lb/in³) | | **Melting Point** | ~ 649 °C (~ 1200 °F) | | **Thermal Conductivity** | 112 W/m·K (at 25°C) | | **Coefficient of Thermal Expansion** | 26.1 µm/m·°C (20 - 100°C) | | **Modulus of Elasticity (Tension)** | 45 GPa (6.5 x 10⁶ psi) | | **Specific Heat Capacity** | ~ 1050 J/kg·K | --- #### **3. Mechanical Properties (Typical for HK31A-H24 Temper)** The H24 temper provides a excellent combination of strength and workability for formed components. The values below are typical for sheet and plate products. **Room Temperature Properties (Typical Minimums):** * **Ultimate Tensile Strength:** 241 MPa (35,000 psi) * **Tensile Yield Strength (0.2% Offset):** 172 MPa (25,000 psi) * **Compressive Yield Strength:** 138 MPa (20,000 psi) * **Elongation:** 4% (in 2 inches) **Elevated Temperature Performance:** The key advantage of HK31A is its performance at high temperatures. For example: * At **260°C (500°F)**, it can maintain a tensile yield strength of approximately **124 MPa (18,000 psi)**. * At **315°C (600°F)**, it can maintain a tensile yield strength of approximately **110 MPa (16,000 psi)**. * It exhibits excellent **creep resistance** and microstructural stability under prolonged exposure to heat. --- #### **4. Product Applications** Magnesium HK31A-H24 is primarily specified for high-performance applications where light weight and high-temperature capability are paramount. * **Aerospace & Defense:** * Skin and structural panels for missiles and rockets. * Fuselage and wing skins for high-speed aircraft. * Heat shields and engine cowlings. * **Aviation:** * Gearbox housings and accessory casings. * Compressor housings in gas turbine engines. * **Spacecraft:** Components subjected to aerodynamic heating during re-entry or ascent. * **Nuclear Industry:** Used selectively for shielding and structural components due to thorium's neutron absorption properties. --- #### **5. International Standards** Magnesium HK31A-H24 is covered by the following key international and aerospace standards. | Standard Organization | Standard Designation & Title | | :--- | :--- | | **ASTM International** | **ASTM B90 / B90M** - Standard Specification for Magnesium-Alloy Sheet and Plate | | **Aerospace Material (AMS)** | **AMS 4383** - Sheet and Plate, Magnesium Alloy HK31A-H24 | | **UNS Number** | **M13310** | | **SAE** | **AMS 4385** - Extruded Shapes and Bars, HK31A (Covers other tempers) | --- #### **Key Advantages & Considerations** * **Advantages:** * **Excellent Elevated Temperature Properties:** Superior strength retention and creep resistance compared to most other magnesium alloys. * **Outstanding Strength-to-Weight Ratio:** One of the lightest structural metals available for high-temperature service. * **Good Fabricability:** Can be welded, formed, and machined satisfactorily with proper techniques. The H24 temper offers a good balance for forming operations. * **Dimensional Stability:** Maintains shape and size under long-term thermal exposure. * **Considerations:** * **Thorium Content:** Thorium is a low-level radioactive element. Machining and grinding operations require controls to manage pyrophoric chips and dust, and disposal must follow regulations for radioactive materials. * **Corrosion Resistance:** Requires protective treatments (e.g., chemical conversion coatings, anodizing, paint) for use in corrosive environments, especially where salt spray is present. * **Modern Alternatives:** Due to handling concerns with thorium, alloys like **WE43 (Mg-Y-Nd-Zr)** and **Elektron 21 (Mg-Gd-Nd-Zr)** are often preferred for new designs, offering similar high-temperature performance without radioactivity. **Conclusion** Magnesium HK31A-H24 (UNS M13310) is a specialized, premium aerospace alloy chosen for its proven performance in extreme thermal environments. Its combination of light weight, high strength, and exceptional stability at temperatures up to 315°C makes it a critical material for missile, rocket, and jet engine applications, despite the handling requirements associated with its thorium content.

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 3335 gallon liquid totes Special package is available on request.