SAE J 451-1976 Aluminum Alloys - Fundamentals.pdf

1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro

2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8512 FAX: (412) 776-0243TO PLACE A DOCUMENT

3、 ORDER; (412) 776-4970 FAX: (412) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1989 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTJ451REAF.JAN89Issued 1934-01Reaffirmed 1989-01Supercedi

4、ng J451bALUMINUM ALLOYS - FUNDAMENTALSForewordThis Document has not changed other than to put it into the new SAE Technical Standards BoardFormat.1. Scope1.1 PurposeThis information report is intended to give general data on the properties of aluminum andinformation on working, joining, forming, mac

5、hining, finishing, and heat treating of aluminum.2. References2.1 Applicable PublicationThe following publication forms a part of the specification to the extent specifiedherein. Unless otherwise indicated the lastest revision of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE,

6、400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J454 AUG87General Data on Wrought Aluminum Alloys3. PropertiesCommercially pure aluminum is a face-centered cubic metal with a specific gravity of about 2.71(0.098 lb/in3), a thermal conductivity of about 0.52 cgs units (at 25C), and a melting po

7、int of approximately1215 F. Its coefficient of thermal expansion (approximately 0.000013 per F) is about twice that of steel orcast iron and about one-third greater than that of copper or brass. The electrical conductivity of purealuminum is about 62% of the International Annealed Copper Standard. I

8、n the form of cast test bars, thecommercially pure metal has a typical tensile strength of 14 000 psi and a typical elongation of 30% in 2 in,while sheet in the annealed temper has a typical tensile strength of about 13 000 psi and a typical elongationof about 45% in 2 in. The modulus of elasticity,

9、 for all practical purposes, is 10 000 000 psi. The commerciallypure metal and many of its alloys are highly resistant to atmospheric corrosion and to attack by manychemicals, with the notable exception of strong alkalis. Because it is so high in the electrochemical series,however, it is subject to

10、galvanic attack if coupled with metals such as the copper alloys in the presence of anelectrolyte.SAE J451 Reaffirmed JAN89-2-4. Alloying ElementsAdditions of alloying elements usually increase the specific gravity (silicon andmagnesium lower it), decrease the electrical and thermal conductivity and

11、 the melting point, increase thestrength, and have a rather slight effect on the coefficient of thermal expansion and the modulus of elasticity.Some alloying elements, alone or in combination, produce alloys that respond to heat treatment. The additionof alloying elements can increase or decrease co

12、rrosion resistance, depending on the alloying element, heattreatment, and service environment. Aluminum alloys which are adversely affected by such additions are oftenprotected by metallurgical cladding with a sacrificial alloy. The alloying elements commonly used in thiscountry are copper, silicon,

13、 magnesium, manganese, and zinc.5. Working And Heat TreatingAluminum and its commercial alloys, being rather ductile materials, can be hotor cold worked into most of the common manufactured forms. The commercially pure metal and some of thealloys are not heat treatable compositions, and attain their

14、 strengths either by virtue of the alloy content orbecause of strain hardening resulting from cold work. The strength of many of the alloys, however, can befurther increased by suitable heat treatments.The response of an aluminum alloy to heat treatment depends on the presence of one or more alloyin

15、gelements substantially more soluble in aluminum at temperatures of about 900 1000F than at roomtemperature. By heating the material for a sufficient time at the proper solution treating temperature, thealloying elements are substantially dissolved by the aluminum; and by quenching rapidly from the

16、solutiontreating temperature, the elements are retained in solid solution. Longer heating times are required forcastings than for wrought products, and for heavy as compared to light sections. Alloys which are susceptibleto intergranular corrosion should be quickly quenched after solution heat treat

17、ment to prevent reprecipitationalong grain boundaries.Certain of the heat treatable alloys, notably the so-called duralumin (Cu, Mg, Si) type alloys, age hardenconsiderably at room temperature within a few days after quenching; the others, although they harden slowly atroom temperature, must be heat

18、ed to about 300F for a few hours to attain their maximum strengths. With afew exceptions, most alloys which age harden substantially at room temperature can be made to develop evengreater strength by a precipitation treatment at 300 500F. It is generally agreed that precipitation treatmentsor age ha

19、rdening result from lattice strains and the precipitation of alloying elements or compounds from thesupersaturated solid solution in the form of minute particles. Recent studies indicate that the strengthening ofheat treatable aluminum alloy by aging is due to both the uniform dispersion of a finely

20、 dispensedsubmicroscopic precipitate and the distortion of the lattice structure by these particles before they reach avisible size. It is believed that these particles, because of their critical size and location in the crystal structure,impede or prevent slip and thus increase the strength of the

21、metal. Because of this phenomenon, these agingtreatments are normally referred to as precipitation treatments. Room temperature aging, on the other hand, isbelieved to be the result of zone hardening. In this connection, it is interesting to note that the better workabilityof the as-quenched materia

22、l can be retained in those alloys which age at room temperature by the simpleexpedient of storing the quenched material at about 0F.The effects of either cold work or heat treatment on the strength and workability of the materials can beremoved by annealing at temperatures of about 600 800F, dependi

23、ng on the alloy and temper. It must beremembered, however, that the strength of a non-heat treatable alloy can be regained, after annealing, only bythe introduction of additional cold work.6. JoiningAluminum and its alloys can be joined by fusion welding, resistance welding, soldering, brazing, anda

24、dhesive bonding. The choice of process is dependent on alloy composition, material thickness, jointconfiguration, and expected service environment. The inert gas shielded metal arc process (MIG) and inertgas shielded tungsten arc process (TIG) are the most widely used fusion welding processes. Oxyga

25、s andcoated electrode welding techniques are sometimes used, but the fluxes required with these processes, if notcompletely removed after welding, can promote corrosion. Brazing techniques now in common use includetorch, dip, and furnace brazing.SAE J451 Reaffirmed JAN89-3-All aluminum alloys can be

26、 joined by one or more of the available processes. Heat treated aluminum alloys(like the ferrous base alloys) are subject to reductions in strength after welding. Heat treating after welding willrestore most of the prewelded mechanical properties. Work hardened aluminum alloys provide good as-welded

27、 mechanical properties and are used for applications such as storage tanks, boats, ships, and railroadcars.7. FormingAluminum and its alloys can be formed hot or cold with considerable ease, although the bend radiifor cold forming and the allowance for spring-back must be increased as the strength o

28、f the material increases.For severe forming, very deep drawing, or spinning, the annealed (0) temper usually is employed; while for theless drastic operations, the intermediate, cold-worked temper (H12, H22, H32; or H14, H24, or H34), or the T3or T4 type temper immediately after quenching usually is

29、 selected. The full hard (H18, H28, or H38) or theheat treated and aged (T6) tempers are not usually used where more than slight forming is required. Heattreatable alloys, however, can often be formed in the annealed or the as-quenched tempers and subsequentlyheat treated to the desired temper.8. Ma

30、chiningThe aluminum alloys can generally be machined easily, if suitable practices and proper tools areused. Substantial tonnages of aluminum alloy rods and bars are regularly used for making screw-machineproducts.9. Finishing And CoatingThe aluminum alloys can be given a wide variety of mechanical,

31、 chemical,electrochemical, or paint finishes. The more common mechanical finishes include sand or grit blasting, scratchbrushing, and buffing, while the chemical finishes may be a simple dip coating or an etching treatment. Thepossibility of generating an explosive mixture of finely powdered metal a

32、nd air should be borne in mind inconnection with mechanical finishing operations. Paint coatings may be either a clear lacquer or a pigmentedcoating and may be applied to secure either decoration or protection, or both. Paint adhesion is generallyenhanced by the application of chemical conversion co

33、atings prior to painting. Electroplating, although notextensively practiced in the past, is now gaining increased commercial use.Anodic coatings can be produced to provide good protection against corrosion and are also good bases forsubsequent paint coatings. These coatings can be dyed, and they mak

34、e possible a variety of colored surfacessuitable for many decorative applications. Their hard, wear resistant surfaces are made use of in manyapplications.The appearance of automotive bright anodized trim parts produced from 5252 or the 5X57 type sheet or a6463 extrusion is dependent upon the alloy,

35、 the temper, the finishing procedure, the aluminum producerscontrols of their fabrication procedures, and the metal handling and forming techniques used. Strengthrequirements and formability considerations generally dictate alloy selections. Variations of temper within thebright sheet trim alloys of

36、fer further opportunity to adjust mechanical and formability properties. However, therelationship between alloy, temper, and appearance must be given careful consideration. Alloy 5457-0, widelyused, has excellent formability associated with the annealed temper. It offers a good and acceptable finish

37、 formany decorative trim parts, but lacks the image clarity or brightness of the less workable strain hardenedtempers, such as the H25 and H28 tempers of all 5X57 type automotive trim alloys. Alloy 5657, when suppliedin a modified strain hardened temper to achieve a higher minimum elongation, may ha

38、ve formability andfinishing capabilities intermediate between the annealed and H25 tempers. Partially recrystallized structures,which may be experienced when material is produced to significantly higher minimum elongation requirementsthan those specified herein for the H25 temper, may give, under so

39、me conditions, an undesirable appearanceafter forming and finishing. Adequate control of finishing procedures is required to provide the highly lustrousand good image clarity possible using the 5X57 type decorative aluminum trim alloys. “Out-of-control“ finishingprocedures used after forming can pro

40、duce trim parts having an unfavorable appearance or corrosionresistance. Improper handling and forming techniques can also contribute to an undesirable appearance(scratches, gouges, strains, etc.) of the final automotive trim part.SAE J451 Reaffirmed JAN89-4-To simplify presentation of information a

41、bout the aluminum alloys, the materials have been grouped under thegeneral headings of casting alloys and wrought alloys. Generally speaking, a given composition is not usedcommercially for both wrought and cast products, and the casting alloys usually contain a somewhat greatertotal alloy content t

42、han the wrought alloys. When yield strength is specified, it is that stress at which the stress-strain curve deviates 0.2% from the modulus line (normally referred to as 0.2% offset).Additional information on aluminum alloys and commercially available forms can be found in SAE J454.PREPARED BY THE S

43、AE WROUGHT ALUMINUM COMMITTEESAE J451 Reaffirmed JAN89RationaleNot applicableRelationship of SAE Standard to ISO StandardNot applicable.ApplicationThis information report is intended to give general data on the properties of aluminum andinformation on working, joining, forming, machining, finishing, and heat treating of aluminum.Reference SectionSAE J454 AUG87General Data on Wrought Aluminum AlloysDeveloped by the SAE Wrought Aluminum Committee