Magnesium HM21A-F,UNS M13210,E FOUR

### **Product Datasheet: Magnesium Alloy HM21A-F (UNS M13210)** **Introduction** Magnesium Alloy HM21A-F is a high-temperature, heat-treatable wrought magnesium alloy primarily strengthened by thorium. It is renowned for its excellent creep resistance and sustained mechanical properties at elevated temperatures, typically up to 315°C (600°F). This sheet alloy is supplied in the strain-hardened (F) temper and is designed for applications where low density and high strength-to-weight ratio are critical under thermal stress. **Key Features** * **Excellent Creep Resistance:** Maintains strength and dimensional stability at temperatures up to 315°C (600°F). * **High Strength-to-Weight Ratio:** As a magnesium alloy, it offers significant weight savings over aluminum and steel. * **Good Fabricability:** Can be formed and welded using standard techniques for magnesium alloys. * **Heat Treatable:** Can be aged to enhance its mechanical properties. --- #### **1. Chemical Composition (Weight %)** The nominal composition of HM21A-F conforms to the following standard limits: | Element | Content (%) | | :------------ | :----------------------: | | **Thorium (Th)** | 1.8 - 2.5 | | **Manganese (Mn)** | 0.45 - 1.0 | | **Magnesium (Mg)** | Remainder | | **Other Impurities** | ≤ 0.30 (total) | *Note: The presence of Thorium classifies this as a low-level radioactive material, which may be subject to specific handling, shipping, and disposal regulations. This has led to a decline in its use in favor of non-thorium-containing alloys like WE43 or Elektron 21 in many new applications.* --- #### **2. Physical Properties** | Property | Value | | :---------------- | :-------------------------------------------- | | **Density** | 1.78 g/cm³ (0.064 lb/in³) | | **Melting Point** | ~ 649°C (1200°F) | | **Thermal Conductivity** | 112 W/m·K (77 Btu·ft/(h·ft²·°F)) | | **Coefficient of Thermal Expansion** | 26.1 µm/m·K (14.5 µin/in·°F) at 20-100°C | | **Electrical Resistivity** | ~ 150 nΩ·m | | **Modulus of Elasticity** | 45 GPa (6.5 x 10⁶ psi) | --- #### **3. Mechanical Properties (Typical for Sheet, Room Temperature)** Properties are typical for material in the as-fabricated (F) temper. | Property | Value | | :---------------- | :-------------------------------------------- | | **Tensile Strength** | 215 MPa (31,000 psi) | | **Yield Strength (0.2% Offset)** | 124 MPa (18,000 psi) | | **Elongation** | 9% | | **Compressive Yield Strength** | 110 MPa (16,000 psi) | **Elevated Temperature Properties:** HM21A retains a significant portion of its strength at high temperatures, which is its primary advantage. * **At 315°C (600°F):** * Tensile Strength: ~ 110 MPa (16,000 psi) * Creep Strength: Excellent resistance under sustained loads. --- #### **4. International Standards** Magnesium HM21A-F is covered by several international and historical standards. * **ASTM:** **ASTM B90 / B90M** - Standard Specification for Magnesium-Alloy Sheet and Plate. * **AMS:** **AMS 4383** - Sheet and Plate, Magnesium Alloy HM21A, Strain-Hardened. * **UNS:** **M13210** * **SAE:** **AMS 4383** * **Federal Standard:** **QQ-M-56** --- #### **5. Product Applications** Due to its high-temperature performance, HM21A-F has been historically used in demanding aerospace and military applications. Its use today is often for legacy systems or specific niches. * **Aerospace:** * **Missile & Rocket Skin and Structures:** Withstands aerodynamic heating. * **Aircraft Engine Components:** Covers, housings, and access panels near engine bays. * **Supersonic Aircraft Skin Panels:** Early designs for aircraft operating at high speeds. * **Gas Turbine Components:** * **Nuclear Applications:** (Historical, related to its thorium content). **Fabrication Notes:** * **Welding:** Can be welded using Gas Tungsten Arc Welding (GTAW/TIG) techniques. * **Forming:** Requires heating for forming operations (hot forming). * **Machining:** Exhibits excellent machinability, typical of magnesium alloys. --- **Disclaimer:** This information is provided for reference purposes. Properties can vary based on manufacturing process, lot, and section thickness. Users must evaluate the suitability of the material for their specific application, especially considering the regulatory aspects of thorium. Always consult the latest official material specifications from the standards organizations for design and procurement.

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 3337 gallon liquid totes Special package is available on request.