Magnesium AZ31B，UNS M11311,E FOUR

Magnesium AZ31B (UNS M11311) Wrought Alloy Product Introduction** **Product Description:** Magnesium AZ31B (UNS M11311) is one of the most commercially popular and widely used wrought magnesium alloys in the world. It is renowned for its excellent combination of properties, including an exceptionally low density, good strength-to-weight ratio, solid ductility, and improved corrosion resistance compared to earlier magnesium alloys. As a wrought product, it is available in forms such as sheet, plate, and extrusions, which can be further processed and heat-treated (brought to various tempers) to suit specific application needs. Its common nomenclature, **Mg-3Al-1Zn**, highlights its primary alloying elements. --- #### **1. Chemical Composition (Weight %)** The chemical composition is strictly controlled, with particular attention to impurity limits to ensure optimal corrosion performance. | Element | Minimum (%) | Maximum (%) | Key Function | | :--- | :--- | :--- | :--- | | **Aluminum (Al)** | 2.5 | 3.5 | Primary strengthener; improves castability and strength. | | **Zinc (Zn)** | 0.6 | 1.4 | Enhances strength and corrosion resistance. | | **Manganese (Mn)** | 0.2 | 1.0 | Essential for improving corrosion resistance, particularly against saltwater, by neutralizing iron impurities. | | **Silicon (Si)** | - | 0.10 | Impurity control. | | **Copper (Cu)** | - | 0.05 | Impurity control (minimized for corrosion resistance). | | **Iron (Fe)** | - | 0.005 | Impurity control (strictly limited for corrosion resistance). | | **Nickel (Ni)** | - | 0.005 | Impurity control (strictly limited for corrosion resistance). | | **Other Elements** | - | 0.30 (total) | - | | **Magnesium (Mg)** | **Balance** | | | *Note: The "B" suffix in AZ31B signifies stricter control over iron, copper, and nickel impurities, which is critical for its enhanced corrosion resistance compared to the older AZ31A grade.* --- #### **2. Physical Properties** | Property | Value / Description | Condition | | :--- | :--- | :--- | | **Density** | 1.77 g/cm³ (0.064 lb/in³) | At 20°C | | **Melting Point** | ~ 605 - 630 °C (1121 - 1166 °F) | - | | **Thermal Conductivity** | 76 - 96 W/m·K | At 25°C | | **Coefficient of Thermal Expansion** | 26.0 μm/m·°C | 20 - 100°C | | **Electrical Resistivity** | ~ 92 nΩ·m | At 20°C | | **Modulus of Elasticity** | 45 GPa (6.5 x 10⁶ psi) | - | | **Shear Modulus** | 17 GPa (2.4 x 10⁶ psi) | - | | **Poisson's Ratio** | 0.35 | - | --- #### **3. Mechanical Properties (Typical Range)** Mechanical properties vary significantly with product form (sheet, plate, extrusion) and temper. The values below represent a typical range for common forms like sheet. | Property | Typical Value Range | | :--- | :--- | | **Tensile Strength** | 255 - 290 MPa (37 - 42 ksi) | | **Yield Strength (0.2% Offset)** | 150 - 220 MPa (22 - 32 ksi) | | **Elongation** | 8 - 21% | | **Hardness** | 55 - 65 HB | *Common Tempers:* * **O (Annealed):** Maximum ductility, lower strength. * **H24 (Strain-Hardened & Partially Annealed):** The standard for sheet; excellent balance of strength and formability. * **F (As-Fabricated):** Properties from the forming process. --- #### **4. International Standards** AZ31B is specified in numerous international standards across different product forms. | Standard Organization | Standard Designation | | :--- | :--- | | **ASTM International** | **ASTM B90** (Sheet and Plate)
**ASTM B107/B107M** (Extruded Rod, Bar, Shapes) | | **SAE International** | **SAE J465** | | **UNS (Unified Numbering System)** | **M11311** | | **ISO (International Org. for Standardization)** | **ISO 3116** (Wrought Magnesium and Magnesium Alloys) | | **AMS (Aerospace Material Spec.)** | **AMS 4375** (Sheet and Plate) | --- #### **5. Product Applications** The high strength-to-weight ratio and good formability of AZ31B make it a prime candidate for weight-critical applications across industries. * **Aerospace:** * Aircraft skin and fuselage panels * Interior components (seats, partitions, flooring) * Wing components, ribs, and brackets * Avionics and electronics housings * **Automotive:** * Seat frames * Steering wheels and column components * Transmission housings and casings * Inner door panels and trunk lids * **Electronics:** * Laptop and tablet casings * Frames for smartphones and portable devices * Housings for cameras, projectors, and hard disk drives * **General Industry & Consumer Goods:** * Portable tool housings (e.g., chainsaws, drills) * Sports equipment (e.g., baseball bats, tennis rackets, climbing gear) * Jigs, fixtures, and lightweight handling equipment --- #### **6. Key Characteristics & Considerations** * **Advantages:** * **Extremely Lightweight:** ~35% lighter than aluminum and ~78% lighter than steel. * **High Specific Strength:** Excellent strength-to-weight ratio. * **Good Damping Capacity:** Superiorly absorbs vibration and noise. * **Excellent Machinability:** Can be machined at high speeds with excellent surface finish and low energy consumption. * **Good Formability (at elevated temps):** Can be hot formed into complex shapes. * **Considerations:** * **Corrosion:** Requires protective coatings (e.g., anodizing, painting) for use in severe environments, especially salt-spray. Its performance is adequate in normal atmospheres. * **Low Strength at High Temperatures:** Mechanical properties degrade significantly above ~120°C (250°F). * **Flammability:** Fine chips, turnings, and powder are highly flammable; proper machining and handling procedures are mandatory. **Summary:** **Magnesium AZ31B (UNS M11311)** is a versatile, high-performance wrought alloy that serves as a cornerstone material for lightweighting strategies. Its favorable property mix makes it an essential engineering material in the aerospace, automotive, and electronics industries, where reducing mass is directly linked to improved performance, efficiency, and portability.

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 3295 gallon liquid totes Special package is available on request.