Magnesium HM31A-F，UNS M13312; ,E FOUR

### **Product Datasheet: Magnesium Alloy HM31A-F (UNS M13312)** **Introduction** Magnesium Alloy HM31A-F is a high-temperature wrought magnesium alloy known for its excellent creep resistance and good strength at elevated temperatures. Unlike the earlier HM21A alloy which uses thorium, HM31A is strengthened by rare earth elements (specifically Cerium and Neodymium) and zirconium. This composition eliminates the low-level radioactivity and associated handling concerns of thorium-containing alloys, making HM31A a more environmentally friendly and easier-to-use alternative for high-temperature applications. The "-F" temper indicates the material is in the as-fabricated state. **Key Features** * **Excellent Creep Resistance:** Maintains strength and dimensional stability at temperatures up to 345°C (650°F) and higher. * **Thorium-Free:** Contains rare earth elements instead of thorium, avoiding regulatory restrictions and handling concerns. * **Good Strength-to-Weight Ratio:** Offers significant weight savings over aluminum and steel alloys at high temperatures. * **Good Fabricability:** Can be formed and welded using standard techniques for magnesium alloys. --- #### **1. Chemical Composition (Weight %)** The nominal composition of HM31A-F conforms to the following standard limits: | Element | Content (%) | | :---------------- | :---------------------------------- | | **Rare Earths (RE)** * | 2.5 - 3.5 | | **Manganese (Mn)** | 0.10 - 0.40 | | **Zirconium (Zr)** | 0.45 - 0.90 | | **Magnesium (Mg)** | Remainder | | **Other Impurities** | ≤ 0.30 (total) | *Note: The rare earth mix is typically rich in Cerium (Ce) and Neodymium (Nd).* --- #### **2. Physical Properties** | Property | Value | | :---------------------------- | :-------------------------------------------- | | **Density** | 1.80 g/cm³ (0.065 lb/in³) | | **Melting Point** | ~ 645°C (1195°F) | | **Thermal Conductivity** | 105 W/m·K (72 Btu·ft/(h·ft²·°F)) | | **Coefficient of Thermal Expansion** | 25.2 µm/m·K (14.0 µin/in·°F) at 20-100°C | | **Modulus of Elasticity** | 45 GPa (6.5 x 10⁶ psi) | --- #### **3. Mechanical Properties (Typical for Sheet/Plate, F Temper)** Properties are representative for material in the as-fabricated condition. **Room Temperature Properties:** | Property | Value | | :----------------------------- | :-------------------------------------------- | | **Tensile Strength, Ultimate** | 255 MPa (37,000 psi) | | **Tensile Strength, Yield (0.2% Offset)** | 172 MPa (25,000 psi) | | **Elongation** | 6% | | **Compressive Yield Strength** | 138 MPa (20,000 psi) | **Elevated Temperature Properties:** HM31A-F retains its strength better than many other magnesium alloys at high temperatures. * **At 345°C (650°F):** * Tensile Strength: ~ 110 MPa (16,000 psi) * **Creep Strength:** Outstanding resistance to deformation under sustained stress, outperforming many aluminum alloys at comparable temperatures. --- #### **4. International Standards** Magnesium HM31A-F is covered by several international standards. * **ASTM:** **ASTM B90 / B90M** - Standard Specification for Magnesium-Alloy Sheet and Plate (Covers HM31A). * **AMS:** **AMS 4392** - Sheet and Plate, Magnesium Alloy HM31A, As-Fabricated (F Temper). * **UNS:** **M13312** * **SAE:** **AMS 4392** --- #### **5. Product Applications** HM31A's primary advantage is its high-temperature capability without the use of thorium, making it suitable for modern aerospace and racing applications. * **Aerospace:** * **Engine Components:** Engine cowlings, gearbox covers, and accessory housing covers where temperatures are elevated. * **Missile and Rocket Components:** Skin panels, fins, and structural parts subjected to aerodynamic heating. * **Helicopter Transmission Housings:** Areas requiring light weight and good strength at moderate temperatures. * **High-Performance Automotive:** * **Racing Engine Components:** Pistons, cylinder heads, and transmission cases in motorsports where weight reduction is critical. * **General Engineering:** * **Jigs and Fixtures:** For use in high-temperature manufacturing environments like autoclaves. **Fabrication Notes:** * **Welding:** Can be readily welded using Gas Tungsten Arc Welding (GTAW/TIG) techniques. The rare earth content helps prevent microporosity and improves weld integrity. * **Forming:** Requires hot forming techniques, typically in the temperature range of 290-345°C (550-650°F). * **Machining:** Exhibits excellent machinability, typical of magnesium alloys. --- **Disclaimer:** This information is provided for reference purposes only. Properties can vary based on manufacturing process, product form (sheet, plate, extrusion), lot, and section thickness. It is essential to consult the latest official material specifications from the relevant standards organizations (e.g., ASTM, SAE) for design, procurement, and manufacturing. The suitability of the material for any specific application must be evaluated by the user.

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 3340 gallon liquid totes Special package is available on request.