SAE ARP 6256-2014 Magnesium Alloys in Aircraft Seats - Engineering Design and Fabrication Recommended Practices.pdf

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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/ARP6256 AEROSPACE RECOMMENDED PRACTICE ARP6256 Issued 2014-12 Magnesium Alloys in

5、 Aircraft Seats - Engineering Design and Fabrication Recommended Practices RATIONALE This document is a guide to the application of magnesium alloys in aircraft seats. This document acts as a guide to support this technology by providing design engineers and project managers with guidelines for the

6、appropriate use of magnesium alloys, advice of fabrication techniques that are unique to magnesium and an overview of the available forms of the material. FOREWORD Magnesium metal is used in a diverse range of markets and applications exploiting the unique physical and mechanical properties of the e

7、lement and its alloys. The light weight properties of magnesium alloys are used as a means of reducing weight, increasing fuel efficiency and reducing greenhouse gas emissions. Compared to magnesium on a volume for volume basis, aluminum weighs one and a half times as much, while steel is four times

8、 as heavy. The use of magnesium in aircraft seat production has been hindered by specification and regulation. There are developments within the SAE and regulatory organizations to remove these restrictions thus allowing magnesium/alloy usage in this and potentially other areas of the aircraft. Due

9、to the existing restrictions, information on the engineering and fabrication of magnesium alloy components is not available. This ARP has been requested by the SAE Aircraft Seat Committee to help define design and fabrication best practices. This document is in support of AIR6160. Magnesium is well

10、known for its low density, but it also has a number of other beneficial attributes. Magnesium alloys have an excellent strength to weight ratio, good fatigue strength and high damping capacity. Magnesium is non-magnetic, has good thermal and electrical conductivity and offers electromagnetic shieldi

11、ng capabilities that match aluminum in electrical enclosures. Magnesium sheet offers very good dent resistance. Magnesium can be shaped by all metal working techniques. It can be cast, extruded, processed via powder metallurgy and rolled into sheet and plate. Magnesium is the easiest of all structur

12、al metals to machine, and can be formed into shapes by forging, drawing, spinning, stamping, impact extrusion and superplastic forming to mention but a few metalworking processes. Magnesium products can be joined by welding, adhesive bonding, bolting, screwing, and the use of self-piercing rivets. A

13、ttention to surface protection is important; therefore, pre-treatments followed by appropriate paint nishes are utilized to ensure adequate protection. In addition, electroless and electroplating treatments are also possible where a bright chrome nish is desired. SAE INTERNATIONAL ARP6256 Page 2 of

14、84 Magnesium has a reputation for being highly ammable. While this may be true for nely divided magnesium powders and ribbon, bulk magnesium does not burn until it has been heated to above its melting point (648 C/1198 F for pure metal). Magnesium has been used for over 50 years in demanding high te

15、mperature applications such as jet engines and nuclear reactors without any practical flammability issues. In recent times significant effort has been made to demonstrate the safe usage of magnesium and its alloys in aircraft interior applications. Federal Aviation Administration test results have s

16、hown that in full scale fuselage flammability tests magnesium posed no additional threat to passenger safety relative to other materials present in the cabin interior. For additional details refer to AIR6160. TABLE OF CONTENTS 1. SCOPE 52. REFERENCES 52.1 SAE Publications . 52.2 ASTM Publications 53

17、 MAGNESIUM AS A RAW MATERIAL OR SEMI-FINISHED PRODUCT . 53.1 Magnesium Alloys . 63.2 Castings 73.2.1 Casting Alloys . 73.2.2 Casting Methods . 83.3 Sheet and Plate . 123.3.1 Production of Magnesium Sheet and Plate 123.3.2 Choosing the Correct Sheet and Plate Alloy 123.4 Extrusions . 143.4.1 Extrusi

18、on Process . 143.4.2 Design . 153.4.3 Choosing the Right Alloy . 163.5 Forgings 184. DESIGNING FROM ALUMINUM TO MAGNESIUM . 234.1 Introduction . 234.2 Metallic Materials Property Development and Standardization (MMPDS) . 234.3 Modulus of Elasticity . 244.4 Shear Modulus - Modulus of Rigidity - Poiss

19、ons Ratio 254.5 Shear Strength 264.6 Compressive and Tensile Properties 264.7 Hardness - Bearing Strength 264.8 Abrasion Resistance . 274.9 Interference of Shrink Fit Applications 274.10 Column Strength . 275. MACHINING 285.1 Cutting Power and Machinabilty . 295.2 Speeds, Feed, and Depths of Cuts .

20、295.3 Tooling 305.3.1 Tool Material . 305.3.2 Tool Life 315.3.3 Tool Geometry 315.3.4 Tooling Manufacturers and Suppliers . 325.4 Clamping, Distortion and Tolerances 325.5 Cooling 325.5.1 Dry Machining . 335.5.2 Cooling Gasses . 335.5.3 Mineral Oils . 335.5.4 Water-Miscible Cutting Fluids . 345.5.5

21、Recommendations for Water-Oil Emulsions . 355.6 Swarf and Chip Handling 355.6.1 Swarf and Chip Storage 36SAE INTERNATIONAL ARP6256 Page 3 of 84 5.6.2 Dry Chips, Turnings and Swarf . 365.6.3 Wet Chips, Turnings and Swarf 365.6.4 Swarf and Chip Transport . 365.6.5 Swarf and Chip Disposal and Recycling

22、 . 365.7 Fire Precautions 365.8 Machining Operations . 375.8.1 Turning and Boring . 385.8.2 Milling 395.8.3 Drilling . 395.8.4 Reaming 415.8.5 Tapping . 415.8.6 Threading 425.8.7 End Milling or Countersinking . 425.8.8 Rounding and Broaching 435.8.9 Sawing 435.8.10 Filing 435.8.11 Grinding and Polis

23、hing 435.8.12 Storage and Handling of Parts 436. JOINING 456.1 Mechanical Joining . 456.2 Bolted Joints 456.2.1 Locking Bolts . 456.2.2 Self-Clinching Nuts . 466.2.3 Inserts - Screwed-in 476.2.4 Inserts - Press and Shrink Fit 476.2.5 Choice of Fasteners and Inserts . 486.3 Self-Piercing/Self-Tapping

24、 Screws . 496.4 Threaded Fasteners 506.4.1 Manufacturers of Fastener Systems for Magnesium 506.5 Adhesive Bonding . 516.5.1 Joint Design 536.5.2 Equipment and Materials 557. CUTTING 567.1 Sawing 567.2 Plasma Arc Cutting Magnesium Plate 587.3 Laser Cutting . 597.4 Water Jet Cutting 598. CORROSION 608

25、1 Corrosion Behavior of Unprotected Magnesium Alloys 608.2 The Behavior of Magnesium Components in Service 618.2.1 Surface Contamination . 618.2.2 Unprotected Magnesium Surfaces . 638.2.3 Galvanic Contacts . 648.3 Design . 648.3.1 Method of Assembly 648.3.2 The Position of a Component in Service 64

26、8.3.3 The Effect of Sharp Edges 648.3.4 Designing an Assembly Containing Components Fabricated from Magnesium and Other Metals . 648.4 Summary . 699. SURFACE TREATMENT 709.1 Protection and Surface Treatment of Magnesium 709.2 Temporary Protection for Storage. 709.3 Application of Coatings . 719.3.1

27、Degreasing 719.3.2 Surface Cleaning. 71SAE INTERNATIONAL ARP6256 Page 4 of 84 9.3.3 Surface Pretreatments: Conversion Coatings or Anodizing (Plasma Electrolytic Oxidation, PEO, Coatings) . 739.3.4 Surface Coatings. 779.4 Appendix . 799.4.1 Related Specifications 7910. FLAMMABILITY 7910.1 General Fir

28、e Precautions with Magnesium . 7910.1.1 Grinding . 8010.1.2 Dust Extraction 8010.1.3 Machining (see also Section 4) . 8110.2 Magnesium Storage and Transportation 8110.2.1 Powder, Chips, Granules, and Turnings . 8210.2.2 Transporting Magnesium 8210.3 If There is a Fire 8210.3.1 Smothering Agents 8210

29、4 Employee Training and Response Team . 8311. REFERENCES 8311.1 Publications and Data Sources . 8311.2 Bibliography 8312. NOTES 84SAE INTERNATIONAL ARP6256 Page 5 of 84 1. SCOPE This document is a guide to the application of magnesium alloys to aircraft interior components including but not limited

30、 to aircraft seats. It provides background information on magnesium, its alloys and readily available forms such as extrusions and plate. It also contains guidelines for “enabling technologies” for the application of magnesium to engineering solutions including: machining, joining, forming, cutting,

31、 surface treatment, flammability issues, and designing from aluminum to magnesium. 2. REFERENCES The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in

32、effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2

33、1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AS8049 Performance Standard for Seats in Civil Rotorcraft, Transport Aircraft, and General Aviation Aircraft

34、AIR6160 Magnesium Alloys in Aircraft Seats - Developments in Magnesium Alloy Flammability Testing 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM B80 Standard Specication for Magnes

35、ium-Alloy Sand Castings ASTM B90/B90M Standard Specication for Magnesium-Alloy Sheet and Plate ASTM B94 Standard Specication for Magnesium-Alloy Die Castings ASTM B107/B107M Standard Specication for Magnesium-Alloy Bars, Rods, Proles, Tubes, and Wire ASTM B199 Standard Specication for Magnesium-Allo

36、y Permanent Mould Castings ASTM B293 Standard Practice for Temper Designations of Magnesium Alloys, Cast and Wrought ASTM B403 Standard Specication for Magnesium-Alloy Investment Castings ASTM B661 Standard Practice for Heat Treatment of Magnesium Alloys ASTM B951 Standard Practice for Codication of

37、 Unalloyed Magnesium and Magnesium Alloys, Cast and Wrought 3. MAGNESIUM AS A RAW MATERIAL OR SEMI-FINISHED PRODUCT Magnesium is available in three basic forms for aerospace applications; alloyed ingot for casting, extrusions in the forms of standard bar and rod, as well as tailor designed profiles;

38、 and sheet and plate. Note that forging feed stock is also available, but this is generally cast billet or pre-extruded bar. Similarly, cast block for machining can be obtained. SAE INTERNATIONAL ARP6256 Page 6 of 84 3.1 Magnesium Alloys The following relates to all product forms including castings,

39、 extrusion, sheet and plate: The American Society for Testing and Materials (ASTM) has a standardized designation system for all magnesium alloys. All alloy designations are characterized by two letters and two numbers, which are followed by a series letter. In certain cases a temper designation is

40、included. The initial two letters indicate the primary and secondary alloying elements and their nominal content in weight percent rounded to the nearest integer is shown by the two numbers respectively. This is followed by a serial letter to indicate any revision to the alloy composition, i.e., WE4

41、3C is an alloy with 4 wt.% yttrium; 3 wt.% rare earths, and is the third alloy registered with that basic composition. Table 1 shows alloying elements and their associated letter used in the ASTM designation. Following the alloy designation, it is common for the temper of the material to be indicate

42、d as shown in Table 2 which contains the definitions of the temper letters. The temper designations used are similar to those used in wrought aluminum alloys. Table 1 - Alloy nomenclature A Aluminum N Nickel B Bismuth P Lead C Copper Q Silver D Cadmium R Chromium E Rare Earths S Silicon F Iron T Tin

43、 H Thorium V Gadolinium J Strontium W Yttrium K Zirconium X Any Other L Lithium Y Antimony M Manganese Z Zinc Table 2 - Alloy temper definition General Divisions Subdivisions of -H Subdivisions of -T F - as fabricated. H1, plus one digit - strain hardened only. T1 - cooled and naturally aged. T6 - s

44、olution heat treated and artificially aged. O - annealed (wrought process). H2, plus one digit - strain hardened and partially annealed. T2 - annealed (cast products only). T7 - solution heat treated and stabilized H - strain hardened. T3 - solution treated and cold worked. T8 - solution heat treate

45、d, cold worked and artificially aged. T - thermally treated to a stable temper (other than those above). H3, plus one digit - strain hardened and thermally stabilized. T4 - Solution heat treated. T9 - solution heat treated, artificially aged, and cold worked. W - solution heat treated (unstable). T5

46、 - cooled and artificially aged. For further information on magnesium alloy specifications, refer to the following ASTM documents: x ASTM B80 Standard Specication for Magnesium-Alloy Sand Castings x ASTM B90/B90M Standard Specication for Magnesium-Alloy Sheet and Plate x ASTM B94 Standard Specicatio

47、n for Magnesium-Alloy Die Castings x ASTM B107/B107M Standard Specication for Magnesium-Alloy Bars, Rods, Proles, Tubes, and Wire x ASTM B199 Standard Specication for Magnesium-Alloy Permanent Mould Castings SAE INTERNATIONAL ARP6256 Page 7 of 84 x ASTM B293 Standard Practice for Temper Designations of Magnesium Alloys, Cast and Wrought x ASTM B403 Standard Specication for Magnesium-Alloy Investment Castings x ASTM B661 Standard Practice for Heat Treatment of Magnesium Alloys x ASTM B951 Standard Practice for Codi