PN AlZn6Mg2Cu Bar, CSN 424222, BS 7075 L95 L96 Bars & Rods

Product Description

Cross-referencing across different regional and defense standards, this configuration points to the ultra-high-strength 7000-series (Al-Zn-Mg-Cu) aluminum alloy matrix.

When drawings specify PN AlZn6Mg2Cu, ÄŒSN 424222, or British Aerospace BS L95 / L96, they are addressing regional variants closely aligned with global 7075 specifications. These standards govern high-performance, heat-treatable materials designed for highly stressed aerospace, defense, and heavy engineering structural applications.

1. Unified Standards & Nomenclature Cross-Reference

• Polish Standard (PN): PN-EN AW-7075 / AlZn6Mg2Cu (Older Polish system designated high-zinc structures under the explicit elemental string AlZn6Mg2Cu or PA9 equivalent).

• Czech Standard (ÄŒSN): ÄŒSN 424222 (The historical Czechoslovakian standard for age-hardened Al-Zn-Mg-Cu structural alloys).

• British Aerospace Standards (BS L-Series):

  • BS L95: Specifically covers 7075 aluminum alloy plate or bars supplied in the controlled stretched, precipitation heat-treated condition (T651 / T6511).

  • BS L96: Typically covers the corresponding structural forged or extruded shapes/bars with identical chemistry but distinct aerospace verification procedures.

• Global Equivalents: EN AW-7075, WNr 3.4365, AISI 7075.

2. Chemical Composition Parameters

The metallurgical profile emphasizes a high zinc concentration combined with magnesium to precipitate $MgZn_2$ zones during aging, while copper is kept near 1.5% to dramatically elevate static yield limits.

3. Mechanical Property Requirements for Bars & Rods

When procured as T6 / T651 / T6511 (solution heat-treated and artificially aged/stress-relieved) under British Aerospace or equivalent standards, the minimal performance baselines are exceptionally high for an aluminum alloy:

4. Fabricating & Processing Engineering Notes

• Machinability: Excellent. In the peak-aged condition (T6/L95), the material behaves almost like a mild carbon steel on lathes and mills. It shears cleanly, breaks chips effectively, and easily achieves a bright, high-precision surface finish with standard carbide tooling.

• Stress Relieving (The L95 Advantage): Aerospace specs like BS L95 demand strict stress-relieving via controlled stretching (indicated by the 51 or 511 suffix). This ensures that when machining complex, asymmetrical profiles out of solid round bars or thick plates, the material will not warp or distort due to residual quenching stresses.

• Weldability Constraints: This alloy is universally classified as non-weldable by conventional fusion methods (MIG/TIG). Attempting to weld it causes extensive hot cracking inside the weld pool and severe microstructural degradation in the heat-affected zone. Mechanical fastners or friction stir welding are used instead.

• Corrosion Considerations: Due to the copper content, it is susceptible to atmospheric corrosion if exposed to outdoor moisture without treatment. Protective hard-coat anodizing or defensive priming/coating is strongly recommended. For environments prone to Stress Corrosion Cracking (SCC), a stabilized over-aged temper like T73 is preferred over standard T6.

5. Primary Application Sectors

• Aerospace and Defense: Military aircraft bulkheads, highly-stressed fuselage ribs, upper wing skins, and structural helicopter rotor heads.

• Ordnance Engineering: Missile fins, structural rocket staging rings, and specialized defense instrumentation casings.

• Heavy Machinery Tooling: Heavy-duty gears, highly loaded shafts, blocks for high-pressure plastic injection molds, and hydraulic manifolds where rapid heat transfer must be paired with steel-like yield thresholds.