Luxfer MEL Technologies’ lightweight magnesium extrusion alloys combine weight saving and high mechanical strength to provide a versatile material for use in aircraft interior applications leading to improved customer experience, better fuel efficiency and increased range.
Weight reduction initiatives are being driven by higher fuel costs, greater efficiency and reductions in CO2?emissions for environmental reasons. The weight advantage over aluminium is becoming increasingly important. So too the ease with which to produce complex critical structures and reduce cost. Magnesium is an attractive alternative in the field of advanced materials for aircraft systems of today and the future.
Elektron? 43 lightweight magnesium extrusion alloy developed by Luxfer MEL Technologies, passed rigorous tests conducted by the U.S. Federal Aviation Administration (FAA) Fire Test Working Groups, which subsequently lifted long-standing restrictions on the use of magnesium alloys in commercial aircraft interiors. By following the guidelines Elektron43 alloy is setting the standard for the reintroduction of magnesium into aircraft interior.
What is Elektron??43?
- Elektron? 43: ?The latest wrought magnesium aerospace alloy
- Optimised wrought version of WE43 class of alloys (ASTM designation WE43C)
- WE43B: ?Well known sand casting alloy used in many high performance applications
- Elektron? 43: Available as plate, extrusion, forging stock
- Elektron? 43: High specific strength, high strain hardening behaviour and excellent energy absorption characteristics
- Strain rate up to 500/s generated at specialist test house
- ASTM Designation “WE43C”
- UNS#: M18434
- AMS Specification
- AMS 4371 – Magnesium Alloy, Plate Precipitation Heat Treated
- AMS 4485 Magnesium Alloy, Extrusions Precipitation Heat Treated
- Extrusion data in vs8 of handbook
- Plate data in vs9 of handbook
- Contains -A and -B basis statistical minima
On Aug. 14 2015, the Society of Automotive Engineers (SAE), which develops standards for both the automotive and aviation industries, published SAE AS8049 Revision C, in which a key statement that had previously read “Magnesium alloys shall not be used” was changed to this new wording: “Magnesium alloys may be used in aircraft seat construction provided they are tested to and meet the flammability performance requirements in the FAA Fire Safety Branch document: Aircraft Materials Fire Test Handbook – DOT/FAA/AR-00/12, Chapter 25, Oil Burner Flammability Test for Magnesium Alloy Seat Structure.”
Elektron? 43 and Elektron? 21 are the only magnesium alloys that have already met the cited performance requirements by passing extensive flammability tests conducted by the FAA, including seven full-scale aircraft interior tests (for the complete test report, see http://www.fire.tc.faa.gov/pdf/AR11-13.pdf). Developed specifically for demanding aerospace applications, these alloys are high-performance materials that are designed to withstand high temperatures and be resistant to corrosion. Both alloys have proven, long-term performance records, including critical applications in jet engines and military aircraft.
If you require any further information, please do not hesitate to contact us.AZ80 magnesium alloy – Excellent balance of strength and corrosion performance while being cost effective. Download our extrusion data sheet to find out more. Available off the shelf as bar stock or customised extrusions.
Is your seat too heavy?
Even primary structured seat parts can be successfully redesigned to pass 16G test
Surface protection for Elektron??43
Elektron??43 has inherently good general corrosion resistance (typically <30mpy). However, even though cabin interiors are not an extreme or overly aggressive environment, surface protection is required for improved performance and also to mitigate against galvanic corrosion.
The corrosion protection scheme suitable for aircraft cabin interiors includes:
- Chemical conversion coating
- Plasma Electrolytic Oxidation (PEO)
- Powder coating*
- Sealer (only PEO)*
- Galvanic protection:
- Aluminium alloy washers
- Aluminium alloy anodised shims
- Polymer coated washer*
- Plastic washer*
*Subject to FAR 25.853 (a and d) and ABD0031-(Sections 7.317.4) testing.
Due to current and anticipated environmental legislation that restricts the use of hexavalent chromium chemicals, all treatments and solutions proposed are REACH compliant (Registration, Evaluation, Authorisation and restriction of Chemicals).
Theses readily available options have been deemed most appropriate:
- Chrome free pre-treatments
- PEO coatings
In all cases it is crucial that adequate cleaning is carried out to ensure that the top coat has sufficient adhesion and performance. Cleaning should include the following steps:
- Alkaline degreasing
- Rinsing?(best practice is DI water)
- Acid etching
- Rinsing (again, best practice is DI water rinse)
From our evaluations, the best performance of the recommended conversion coating have been obtained when sufficient cleaning, using the steps detailed above has been carried out.
Cleaning helps with the corrosion protection and adhesion performance of the surface protection system. i.e. helps to avoid delamination and poor performance of the top coat.
Powder coatings proved to be suitable are hybrid epoxy/polyester. Magnesium Elektron has identified a number that comply with the following:
- FAR 25.853 (a and d)
- ABD0031-(Sections 7.3/7.4)
Due to Magnesium and its alloy position in the electrochemical series careful of consideration is required when dissimilar metals are used in intimate contact. While surface treatments and coated fasteners are important but it is equally important to consider how design and layout of the components might reduce the exposure to galvanic attack.