7049-T73; 7049-T7352 Aluminum alloy,Aluminum 7049-T73; 7049-T7352 alloy，E FORU

### **7049-T73 / 7049-T7352 Aluminum Alloy: Ultra-High Strength with Superior Corrosion Resistance** **7049-T73 and 7049-T7352** are specific tempers of the premium 7049 Al-Zn-Mg-Cu alloy. These tempers represent the **final, fully heat-treated condition** of the alloy, where it achieves an optimal balance of **very high strength and exceptional stress corrosion cracking (SCC) resistance**. The T73-type aging process is the key differentiator, making this material a top choice for the most critical safety components in aerospace and defense, such as aircraft landing gear. --- #### **1. Chemical Composition** The composition is that of the base 7049 alloy, designed for maximum strength. | Element | Content (%) (Typical) | Role in the Alloy | | :--- | :--- | :--- | | **Zinc (Zn)** | 7.2 - 8.4 | Primary strengthening element; forms the main hardening precipitates (MgZn₂). | | **Magnesium (Mg)** | 2.0 - 2.9 | Co-operates with Zn to form the strengthening η' phase during aging. | | **Copper (Cu)** | 1.2 - 1.9 | Critically enhances strength and improves resistance to stress corrosion cracking. | | **Chromium (Cr)** | 0.10 - 0.22 | Forms dispersoids that control grain structure and improve toughness. | | **Iron (Fe)** | ≤ 0.15 | Impurity (controlled to maintain toughness). | | **Silicon (Si)** | ≤ 0.12 | Impurity (controlled to maintain toughness). | | **Manganese (Mn)** | ≤ 0.20 | - | | **Titanium (Ti)** | ≤ 0.10 | - | | **Other Impurities** | ≤ 0.05 each; ≤ 0.15 total | - | | **Aluminum (Al)** | Balance | Base metal. | --- #### **2. Understanding the T73 and T7352 Tempers** The temper designation is critical and defines the final properties of the product. * **T73: Solution Heat-Treated and then Artificially Over-Aged.** * This is a two-stage aging process (often referred to as a "retrogression and re-aging" type treatment) that goes beyond the peak strength (T6) condition. * **Purpose:** To deliberately sacrifice a small amount of strength to **dramatically improve the alloy's resistance to Stress Corrosion Cracking (SCC) and exfoliation corrosion.** This trade-off is essential for safety-critical applications. * **T7352: Solution Heat-Treated, Stress-Relieved by Compressing (1-5%), and then Artificially Over-Aged to the T73 condition.** * The **52** suffix indicates the product has been stress-relieved by compression after solution heat treatment. * **Purpose:** The compression provides superior dimensional stability, minimizing distortion during subsequent machining and making it the preferred temper for complex, close-tolerance **forgings** and finished components. In summary: **T7352 is essentially the T73 thermal treatment applied to a product that has been compressively stress-relieved.** --- #### **3. Physical Properties** Physical properties are for the base 7049 alloy in this fully heat-treated condition. | Property | Value / Description | | :--- | :--- | | **Density** | ≈ 2.84 g/cm³ (0.102 lb/in³) | | **Melting Range** | ≈ 475°C - 635°C (887°F - 1175°F) | | **Electrical Conductivity** | ≈ 38-42% IACS (Higher than T6 due to over-aging) | | **Thermal Conductivity** | ≈ 110-130 W/m·K | | **Coefficient of Thermal Expansion** | ≈ 23.2 x 10⁻⁶/°C (20-100°C) | | **Modulus of Elasticity (E)** | ≈ 71 GPa (10.3 x 10⁶ psi) | --- #### **4. Mechanical Properties (Typical)** The T73/T7352 temper provides a robust combination of properties. | Property | Typical Value (T73/T7352) | | :--- | :--- | | **Tensile Strength (Ultimate)** | 530 - 570 MPa (77 - 83 ksi) | | **Tensile Yield Strength (0.2% Offset)** | 460 - 500 MPa (67 - 73 ksi) | | **Elongation (in 50 mm / 2 in)** | 8 - 11 % | | **Hardness (Brinell)** | ≈ 145 - 155 HB | --- #### **5. Product Applications** These tempers are used for final, finished components that require the highest level of performance and reliability. * **Aerospace Industry (Primary Application):** * **Aircraft Landing Gear:** Main fittings, beams, pistons, and bogie beams. * **Airframe Components:** Wing spar chords, fuselage frames, and bulkheads. * **Helicopter:** Rotor head components and dynamic parts. * **Spacecraft and Missile:** Motor casings and high-stress structural rings. * **Defense Industry:** * **Armored Vehicle Components:** Critical structural parts and hatches. --- #### **6. International Standards** These specific tempers are codified in major aerospace standards. | Standard Body | Alloy Designation | Common Forms | Relevant Standard | | :--- | :--- | :--- | :--- | | **Aluminum Association (AA)** | **7049-T7352** | Die Forgings, Hand Forgings | AA Teal Sheets / ANSI H35.1 | | **Aerospace (AMS)** | **7049-T73** | Die Forgings | **AMS 4125** (This is a key specification for 7049-T73 Die Forgings) | | **European Norm (EN)** | **EN AW-7049 T7352** | Forgings | EN 586-2 (Forgings) | | **ASTM International** | **Aluminum 7049** | Forgings | ASTM B247 (Specification for Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings) | --- #### **Key Advantages & Summary** * **Optimal Property Balance:** Offers one of the best available combinations of very high strength and excellent SCC resistance in aluminum alloys. * **Superior Stress Corrosion Cracking (SCC) Resistance:** The T73 over-aging process is specifically designed to make the alloy highly resistant to failure under tension in corrosive environments. * **Good Exfoliation Corrosion Resistance:** Performs well in environments that cause layered corrosion. * **Good Fracture Toughness:** Suitable for damage-tolerant design principles. * **Dimensional Stability (T7352):** The compressive stress-relief makes T7352 ideal for complex components that require precise final machining. In conclusion, **7049-T73 and 7049-T7352 Aluminum Alloys** represent the pinnacle of aluminum alloy technology for high-stress structural applications. The deliberate over-aging of the T73 process transforms the inherently strong 7049 alloy into a exceptionally reliable material, making it the industry standard for critical components like landing gear where failure is not an option.

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 2145 gallon liquid totes Special package is available on request.