Aluminium ENAW-AlZn5.5MgCu Plates & Sheets (EU EN, DIN, WNR)

Product Description

The designation EN AW-AlZn5.5MgCu is the technical chemical name under the European (EN) and International (ISO) systems for the ultra-high-strength alloy commonly known as 7075.

This material represents the pinnacle of aluminum engineering for aerospace and defense, offering a strength-to-density ratio that competes directly with many high-grade steels.

1. Regulatory & Technical Designations

Depending on the region or specific industry (e.g., German automotive vs. European aerospace), you will encounter this material under different names:

2. Chemical Composition (EN 573-3)

The name AlZn5.5MgCu explicitly identifies the primary alloying elements that create its massive strength through precipitation hardening:

• Zinc (Zn) [5.10 “ 6.10 The primary alloying element, responsible for high strength.

• Magnesium (Mg) [2.10 “ 2.90 Works with Zinc to form $MgZn_2$ precipitates.

• Copper (Cu) [1.20 “ 2.00 Increases strength and hardness, though it lowers weldability.

• Chromium (Cr) [0.18 “ 0.28 Helps control grain structure and improves stress corrosion resistance.

3. Standard Tempers for Plates & Sheets

In the EU market, plates and sheets are almost exclusively supplied in these conditions:

• T6: Solution heat-treated and artificially aged. This is the "Peak Strength" condition.

• T651: The most common state for Plates. After quenching, the plate is stretched by a controlled amount ($1.5\% \text{ to } 3\%$) to relieve internal stresses. This ensures the material remains flat and stable during heavy machining.

• T73 / T7351: Over-aged condition. It reduces maximum strength by about 10-15% but significantly improves resistance to Stress Corrosion Cracking (SCC).

4. Mechanical Properties (EN 485-2)

Typical values for EN AW-AlZn5.5MgCu-T651 plates (thickness 12.5mm “ 25mm):

5. Fabrication & Application Guidance

Machining & Stability

This alloy is highly favored by CNC machine shops. It produces excellent surface finishes and predictable chip control. When using WNR 3.4365 blocks or plates, the T651 temper is essential if you are milling deep pockets or asymmetrical shapes, as it prevents the "spring-back" effect.

Corrosion & Protection

Because of its high alloy content, 7075 is prone to atmospheric corrosion.

• Sheets: Often supplied as Alclad, where the 7075 core is covered with a thin layer of 1050 or 7072 aluminum.

• Plates: Usually require Anodizing (Hard, Sulfuric, or Chromic) or high-quality epoxy primers for long-term durability.

Joining

• Welding: Generally considered non-weldable for structural purposes.

• Fastening: Mechanical joining (bolts/rivets) or structural adhesives are the standard assembly methods.

Summary Comparison: 2014A vs. 7075