Magnesium HM21A-T5， UNS M13210;,E FOUR

### **Product Datasheet: Magnesium Alloy HM21A-T5 (UNS M13210)** **Introduction** Magnesium Alloy HM21A-T5 is a high-temperature, heat-treatable wrought magnesium alloy strengthened by thorium. The "-T5" temper designation indicates that the product has been artificially aged after a fabrication process (such as casting or extrusion) that involves a high-temperature shaping step. This temper is designed to develop improved strength and stability, particularly for parts that are not suitable for solution heat treatment after forming. HM21A-T5 is renowned for its excellent creep resistance and good strength-to-weight ratio at elevated temperatures up to 315°C (600°F). **Key Features** * **Good Elevated Temperature Properties:** Offers stable mechanical performance and excellent creep resistance at high temperatures. * **Optimized for As-Fabricated Parts:** The T5 temper is ideal for components that are shaped at high temperatures and then artificially aged to increase strength. * **Low Density:** Provides significant weight savings over aluminum and steel alloys. * **Good Fabricability:** Can be welded and machined using standard techniques for magnesium alloys. --- #### **1. Chemical Composition (Weight %)** The nominal composition of HM21A-T5 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) | ***Important Note:*** *The thorium content classifies this alloy as a low-level radioactive material. This subjects it to specific handling, shipping, and disposal regulations. In many modern applications, it has been superseded by non-thorium, rare-earth containing alloys like WE43 (Mg-Y-RE) or Elektron 21.* --- #### **2.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 | | **Modulus of Elasticity** | 45 GPa (6.5 x 10⁶ psi) | --- #### **3. Mechanical Properties (Typical for T5 Temper)** The T5 temper provides a good balance of strength and stability. Properties can vary significantly between product forms (e.g., extrusions vs. castings). **Typical Room Temperature Properties (Extruded Sections):** | Property | Value | | :----------------------------- | :-------------------------------------------- | | **Tensile Strength, Ultimate** | 200 - 235 MPa (29,000 - 34,000 psi) | | **Tensile Strength, Yield (0.2% Offset)** | 145 - 165 MPa (21,000 - 24,000 psi) | | **Elongation** | 4% - 7% | **Elevated Temperature Properties:** HM21A-T5 is designed to retain its strength under thermal load. * **At 315°C (600°F):** * Tensile Strength: ~ 110 MPa (16,000 psi) * **Creep Strength:** Excellent resistance to deformation under sustained stress. --- #### **4. International Standards** Magnesium HM21A in various tempers, including T5, is covered by several international and historical standards. * **ASTM:** * **ASTM B107 / B107M** - Standard Specification for Magnesium-Alloy Extruded Bars, Rods, Profiles, Tubes, and Wire (Covers T5 temper). * **ASTM B91** - Standard Specification for Magnesium-Alloy Forgings (May cover T5 temper). * **AMS:** **AMS 4377** - Magnesium Alloy Extruded Bars, Rods, Shapes, and Tubes HM21A, Artificially Aged (T5 Temper). * **UNS:** **M13210** * **Federal Standard:** **QQ-M-56** (Covers various tempers) --- #### **5. Product Applications** The HM21A-T5 temper is typically used for components that are formed by processes like extrusion or forging, where the high-temperature shaping process serves as the "solution heat treatment" step, followed directly by aging. * **Aerospace & Defense:** * **Missile Fins and Body Sections:** Extruded profiles used in high-speed airframes subject to kinetic heating. * **Aircraft Engine Components:** Engine mount brackets, support structures, and housings. * **Rocket Components:** Structural parts requiring light weight and thermal stability. * **General Engineering:** * **Jigs and Fixtures:** For use in high-temperature manufacturing environments. **Fabrication & Heat Treatment Notes:** * **The T5 Temper Process:** The material is cooled from an elevated temperature shaping process (like extrusion) and then artificially aged. This is different from T6, which involves a separate solution heat treatment step. * **Welding:** Can be welded using Gas Tungsten Arc Welding (GTAW/TIG). However, welding will alter the metallurgical condition in the Heat-Affected Zone (HAZ), generally reducing strength, and may require post-weld heat treatment. * **Machining:** Exhibits excellent machinability, typical of magnesium alloys. --- **Disclaimer:** This information is for reference purposes only. Properties can vary based on product form (extrusion, forging), section thickness, and specific processing parameters. The thorium content necessitates careful regulatory compliance. 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 3339 gallon liquid totes Special package is available on request.