AA C-6-2015 Aluminum and Its Alloys (Third Edition).pdf

1、Technical Report: Aluminum and Its AlloysAluminum and Its AlloysC-6USE OF THIS INFORMATION Any data and information contained in this paper were compiled and/ or developed by The Aluminum Association, Inc. In the view of the variety of conditions and methods of use to which such data and information

2、 may be applied, The Aluminum Association and its member companies assume no responsibility or liability for the use of information contained herein. Neither The Aluminum Association nor any of its member companies give warranties, express or implied, with respect to this information. Third Edition,

3、 October 2015 TECHNICAL REPORT: ALUMINUM AND ITS ALLOYS THIRD EDITION SEYMOUR G. EPSTEIN TECHNICAL DIRECTOR Revised: October 2015 by J. Gilbert Kaufman THE ALUMINUM ASSOCIATION ABSTRACT Aluminum, especially when alloyed with one or more of several common elements, has been increasingly specified and

4、 used in packaging, architectural, transportation, chemical, electrical and many general applications. Today, aluminum is surpassed only by steel in its use as a structural material. The properties of aluminum and its alloys which give rise to their widespread usage, with particular emphasis on manu

5、facturability, recyclability, and corrosion resistance, are briefly described in this report. The designation system by which alloys are classified is also described, and references are provided for the reader who may desire more detailed information. PREFACE The first edition of this report was pre

6、pared for, and first presented at, The Annual Liberty Bell Corrosion Course, sponsored by The National Association of Corrosion Engineers in Philadelphia, Pennsylvania in September 1978. The original was updated for the Second Edition in 1994. The current 2015 Edition was commissioned by Secat, Inc.

7、 for use in educational classes. Copyright 2015, The Aluminum Association, Inc. Unauthorized reproduction by photocopy or any other method is illegal 5 INTRODUCTION THE MANY ADVANTAGES OF ALUMINUM other elements are also added in smaller amounts for grain refinement and to develop special properties

8、. More recently elements such as silver, lithium and scandium have been used in small quantities for aerospace applications. Since there is a wide variety of aluminum alloys, special designation systems were developed by The Aluminum Association to distinguish the alloys in a meaningful manner and,

9、further, to indicate what metallurgical condition, or temper has been imparted to the alloy. Aluminum and its alloys are divided into two classes according to how they are formed: wrought and cast. The “wrought“ category is indeed a broad one, since aluminum can be formed by virtually every known pr

10、ocess; wrought forms include sheet and plate, foil, extrusions, bar and rod, wire, forgings and impacts, drawn and extruded tubing, and others. Cast alloys are those specially formulated to flow into 6 sand or permanent molds, to be die cast, or to be cast by any other process where the casting is t

11、he final form. Each wrought or cast aluminum alloy is designated by a number to distinguish it as a wrought or cast alloy and to broadly describe the alloy. A wrought alloy is given a four- digit number. The first digit classifies the alloy series or principal alloying modification in the basic elem

12、ent. The second digit, if different than 0 (zero), denotes a modification in the basic alloy. The third and fourth digits form an arbitrary number which identifies the specific alloy in the series.* Variations are identified by a serial letter after the numerical designation e.g. 6005 A. A cast allo

13、y is assigned a three digit number followed by a decimal. Here again the first digit signifies the alloy series or principal addition; the second and third digits identify the specific alloy; the decimal indicates whether the alloy composition is for finished castings (.0) or for ingot (.1 or .2). A

14、 capital letter prefix (A,B, C, etc.) indicates a modification of the basic alloy. The designation systems for aluminum wrought and cast alloys are shown in Tables 1 and 2, respectively. *Note: An exception is for the 1xxx series alloys, where the last two digits indicate the minimum aluminum percen

15、tage. For example, alloy 1060 contains a minimum of 99.60% aluminum. 7 TABLE 1 DESIGNATION SYSTEM FOR WROUGHT ALUMINUM ALLOYS ALLOY SERIES DESCRIPTION OR MAJOR ALLOYING ELEMENT 1XXX 99.00 Minimum Aluminum 2XXX Copper 3XXX Manganese 4XXX Silicon 5XXX Magnesium 6XXX Magnesium and Silicon 7XXX Zinc 8XX

16、X Other Element 9XXX Unused Series TABLE 2 DESIGNATION SYSTEM FOR CAST ALUMINUM ALLOYS ALLOY SERIES DESCRIPTION OR MAJOR ALLOYING ELEMENT 1XX.X 99.00 Minimum Aluminum 2XX.X Copper 3XX.X Silicon plus Copper and/or Magnesium 4XX.X Silicon 5XX.X Magnesium 6XX.X Unused Series 7XX.X Zinc 8XX.X Tin 9XX.X

17、Other Element Note: The authoritative references for all properties and characteristics presented herein are, for wrought alloys, the Aluminum Association publication “Aluminum Standards subdivisions, where required, are indicated by one or more digits following the letter. The basic tempers are: “F

18、“ as fabricated: Applies to products of forming processes in which no special control over thermal or work hardening conditions is employed. Mechanical property limits are not assigned to wrought alloys in this temper, but are assigned to cast alloys in “as cast,“ F temper. “O“ annealed: Applies to

19、wrought products which have been heated to effect recrystallization, produce the lowest strength condition, and cast products which are annealed to improve ductility and dimensional stability. “H“ strain hardened: Applies to wrought products which are strengthened by strain-hardening through cold wo

20、rking; the strain-hardening may be followed by supplementary thermal treatment which produces some reduction in strength. The H is always followed by two or more digits (see Table 3). “W“ solution heat treated: Applies to an unstable temper applicable only to alloys which spontaneously age at room t

21、emperature after solution heat treatment. This designation is specific only when the period of natural aging is indicated; for example, W hr. Solution heat treatment involves heating the alloy to approximately 1000F (540C) to bring the alloying elements into solid solution, followed by rapid quenchi

22、ng to maintain a supersaturated solution to room temperature. “T“ thermally treated: Applies to products which are heat treated, sometimes with supplementary strain hardening, to produce a stable temper other than F or O. The T is always followed by one or more digits (see Table 4). 9 TABLE 3 SUBDIV

23、ISION OF H TEMPERS STRAIN-HARDENED FIRST DIGIT INDICATES BASIC OPERATIONS: H1 -Strain-hardened only H2 -Strain-hardened and partially annealed H3 -Strain-hardened and stabilized SECOND DIGIT INDICATES DEGREE OF STRAIN HARDENING: HX2 - Quarter-hard HX4 - Half-hard HX8 - Full-hard HX9 - Extra-hard THI

24、RD DIGIT INDICATES VARIATION OF TWO-DIGIT TEMPER. TABLE 4 SUBDIVISIONS OF T TEMPERS: THERMALLY TREATED FIRST DIGIT INDICATES SPECIFIC SEQUENCE OF TREATMENTS: T1 - Naturally aged after cooling from an elevated temperature shaping process T2 - Cold worked after cooling from an elevated temperature sha

25、ping process and then naturally aged T3 - Solution heat-treated, cold worked and naturally aged T4 - Solution heat-treated and naturally aged T5 - Artificially aged after cooling from an elevated temperature shaping process T6 - Solution heat-treated and artificially aged T7 - Solution heat-treated

26、and stabilized (over-aged) T8 - Solution heat-treated, cold worked, and artificially aged T9 - Solution heat-treated, artificially aged, and cold worked T10 - Cold worked after cooling from an elevated temperature shaping process and then artificially aged SECOND DIGIT INDICATES VARIATION IN BASIC T

27、REATMENT: Examples: T42 or T62- Heat-treated to temper by user 10 ADDITIONAL DIGITS INDICATE STRESS RELIEF: Examples: TX51 - Stress relieved by stretching TX52 - Stress relieved by compressing TX54 - Stress relieved by stretching and compressing Subdivisions of the H and T tempers are shown in Table

28、s 3 and 4, respectively. There are four basic strain hardening categories: H1, H2, H3 and H4. The second digit indicates the degree of strain hardening. The severely cold worked, or full hard, condition (H18) is usually obtained with a 75% reduction in area. The H19 temper identifies products with s

29、ubstantially higher strengths and greater reduction in area. For H2X tempers, the products are strain hardened more than required and then partially annealed to reduce strength to the desired level. The H3X tempers apply to Al Mg alloys, which tend to age soften at room temperature and are heated at

30、 a relatively low temperature to effect the age softening and thereby provide stable mechanical properties. This results in a slightly lower strength but improved ductility and working characteristics. H4 applies to products which are strain-hardened and which are subjected some thermal operation du

31、ring the subsequent painting or lacquering operation. Basically, heat treatable aluminum alloys will naturally age at room temperature following quenching and will be further strengthened by precipitation hardening. Natural aging following quenching from a high temperature forming process, for examp

32、le casting or extruding, is designated T1. More commonly, natural aging follows solution heat treatment (T4). Artificial aging is accomplished by heating the product to a temperature of roughly 400F (200 C) for several hours (time and temperature depend on the alloy) to accelerate the precipitation

33、process and to further increase the strengthening effect. Here again, artificial aging may follow a quench from a high temperature forming process such as extrusion (T5) or more commonly, following solution heat treatment (T6). The T7 temper indicates over aging from a T6 temper of maximum strength

34、to improve characteristics such as resistance to corrosion. The other T tempers indicate that strain hardening has been employed either to supplement the strengths achieved by precipitation or to increase the response to precipitation hardening. The identifications and nominal chemical compositions

35、of some commonly used aluminum alloys are shown in Tables 5 a cubic foot weighs 170 pounds (2720 kg/mm3)compared to 62 pounds (992 kg/mm3) for water and 490 (7850 kg/mm3)pounds for steel. Pure aluminum melts at 1220F (660C), which is considerably lower than the melting point of most other structural

36、 materials. It is an excellent conductor of heat and electricity. On a volume basis, the electrical conductivity of pure aluminum is roughly 65% of the International Annealed Copper Standard, but pound for pound aluminum is a better conductor than copper, which weighs 565 lbs/ ft3 (8960 kg/mm3). As

37、far as mechanical properties are concerned, pure aluminum has relatively low strength but is highly ductile. Its modulus of elasticity is approximately 10 x 106 psi (70 GPa) compared to 30 x 106 psi (210 GPa) for steel which means that, for a given size and shape and under comparable loading, alumin

38、um will elastically deform three times more than steel but will absorb three times more energy. Aluminum is very tough, and, unlike steel and titanium, aluminum and its alloys do not lose ductility and become brittle at cryogenic temperatures; they are actually tougher near absolute zero than at roo

39、m temperature. Aluminum, like most metals, can be strengthened by strain hardening or cold working to a significant extent. However, much greater strengthening is provided by alloying aluminum with a variety of elements. While commercially pure aluminum (99+% Al) is used for electrical conductors, c

40、hemical equipment and sheet metal work, aluminum alloys are much more widely used, especially where strength is an important consideration. 18 PROPERTIES OF ALUMINUM ALLOYS MECHANICAL PROPERTIES Typical mechanical properties of some commonly used wrought aluminum alloys are shown in Tables 8 and 9 f

41、or non-heat-treatable and heat-treatable alloys, respectively. Non-heat-treatable alloys are those which derive strength from solid solution or dispersion hardening and are further strengthened by strain hardening. They include the 1xxx, 3xxx, some 4xxx, and 5xxx series alloys. Heat-treatable alloys

42、 are strengthened by solution heat treatment and subsequent precipitation hardening, and include the 2xxx, some 4xxx, 6xxx, and 7xxx series alloys. Typical properties are similar to average or mean properties and are higher than specified minimum or design properties. Typical properties are not mean

43、t for design purposes but are useful for comparisons. Casting alloys cannot, of course, be worked hardened and are either used in the as cast or heat-treated conditions. Typical mechanical properties for commonly used casting alloys are presented in Table 10. All aluminum alloys are isotropic. Alumi

44、num composites can be engineered to be anisotropic by layering non-aluminum materials on the surface of an aluminum sheet. The non-aluminum material has directional properties. These composites can be used in aircraft applications to provide greater strength to weight ratios than monolithic aluminum

45、 alloys. Very thin foils, 10 microns and less in thickness can be laminated to paper or plastic substrates to form strong, inexpensive flexible packaging materials. The laminate can be decorated with colored inks for labeling or aesthetic purposes. These thin foils can also be laminated for aseptic

46、packaging applications where the foil forms a barrier to contamination of the package content. Thicker laminates with polypropylene or other plastic materials are used for low cost, high aesthetic property architectural cladding for buildings and as a versatile material for signage. 19 TABLE 8 TYPIC

47、AL MECHANICAL PROPERTIES OF REPRESENTATIVE NON-HEAT TREATABLE ALUMINUM ALLOYS TENSILE STRENGTH TENSILE YIELD STRENGTH ELONGATION BRINELL ALLOY TEMPER ksi MPa ksi MPa % in 2 in. HARDNESS* 1199 O 6.5 45 1.5 10 50 - H18 17 115 16 110 5 - 1100 O 13 90 5 35 35 23 H14 18 125 17 115 9 32 H18 24 165 22 150

48、5 44 3003 O 16 110 6 40 30 28 H14 22 150 21 145 8 40 H18 29 200 27 185 4 55 3004 O 26 180 10 70 20 45 H34 35 240 29 200 9 63 H38 41 285 36 250 5 77 5005 O 18 125 6 40 25 28 H34 23 160 20 140 8 41 H38 29 200 27 185 5 55 5052 O 28 195 13 90 25 47 H34 38 190 31 165 10 68 H38 42 290 37 255 7 77 5083 O 4

49、2 290 21 145 22 - H116 46 315 33 230 16 - H321 46 315 33 230 16 - 5086 O 38 260 17 115 22 - H116 42 290 30 205 12 - H34 47 325 37 255 10 - 5454 O 36 250 17 115 22 58 H32 40 275 30 204 10 73 H34 44 305 35 240 10 81 5456 O 45 310 23 160 24 - H116 51 350 37 255 16 90 H321 51 350 37 255 16 90 *500 kg load on 10 mm ball 20 TABLE 9 TYPICAL MECHANICAL PROPERTIES OF REPRESENTATIVE HEAT TREATABLE ALUMINUM ALLOYS TENSILE STRENGTH TENSILE YIELD STRENGTH ELONGATION BRINELL ALLOY TEMPER ksi MPa ksi MPa % in 2 in. HARDNESS* 2014 O 27 185 14 95 18 45 T6 70 485 60 415 13 135 2024 O 2