ASM Handbook, Volume 14A: Metalworking: Bulk Forming Copyright © 2005 ASM International® S.L. Semiatin, editor, p522-527 All rights reserved. DOI: 10.1361/asmhba0004015 www.asminternational.org Extrusion of Aluminum Alloys Wojciech Z. Misiolek, Lehigh University, and Richard M. Kelly , Werner Co. ALUMINUM AND ALUMINUM ALLOYS Variety of surface finishes ranging from clear many sizes offer many design possibilities and are very suitable for extrusion and many types to color anodized for functional or cosmetic advantages such as: of profiles can be produced from easily ex- applications, as well as painted or plated. trudable alloys (Fig. 1, Ref 1). Aluminum Nontoxic for food storage, cookware, and Design feature Design advantage extrusion is a very competitive technology food processing applications. Near-net shape Optimized cross-sectional for creating profiles for new products with Recyclable. design short lead times, a wide range of properties Variable wall geometry Place metal only where needed Solid, open, and hollow Minimize overall weight associated with various alloys, and design flex- profiles ibility. Aluminum Extrusion Alloys Multivoid hollow designs Avoid secondary machining The widespread use of aluminum extrusions operations is due to the versatility of applications from Legs Allow assembly or joining The relatively inexpensive cost of producing operations the combination of the extruded product form Fins Replacement of multiple parts and the material characteristics of aluminum. aluminum extrusions, coupled with the ease of recycling aluminum, has expanded its many Slots and dovetails Reduce component inventories Applications may be linked to the advantages Screw bosses, hinges, Provide attachment points of extruded profiles, or both. The basic material applications in industry, transportation, house- slides, snap fit, thermal characteristics of aluminum and its alloys hold, and everyday use. As modern technologi- breaks include (Ref 1–7): cally advanced materials, aluminum and its alloys are used in emerging applications as well Table 1 lists some extrusion alloys by alumi- Density approximately one-third that of steel, as revitalizing older designs. Aluminum extru- num alloy series. Ranging from simple to com- copper, brass, or nickel. sions ranging from rod, bar, or tube to complex plex cross sections, aluminum extrusions can be High strength-to-weight ratios with tensile cross-sectional designs find applications in produced in many alloys including the 1xxx yield strength in excess of 550 MPa (80 ksi) transportation, building and construction, elec- (99.00% minimum Al), 2xxx (with Cu), 3xxx for some aluminum alloys. trical, medical, household, and sports products. (with Mn), 5xxx (with Mg), 6xxx (with Mg and Good electrical conductivity: Aluminum The flexible alternatives of the extrusion process Si), and 7xxx (with Zn) alloy series. Of these, the has two times the electrical conductance as and vast array of cross-sectional geometries in predominant alloy group by commercial volume copper on a weight basis, stemming from is the 6xxx series alloys; the year of introduction its lighter mass density and its electrical for several key 6xxx alloys is listed in Table 1. conductivity of 62% IACS (International Table 2 provides a general listing of some typical Annealed Copper Standard) relative to applications for aluminum extrusions using the copper. 6xxx alloy series. Many newer applications, such Good thermal conductivity. as space frames for automobiles or in-line skate Corrosion resistance. rails, are also aluminum extrusions from this Nonmagnetic face-centered cubic (fcc) crys- tal structure for electrical shielding and elec- tronic applications and an excellent reflector Table 1 Aluminum extrusion alloys of electromagnetic waves, including radio and by series radar. Series Alloys Light reflectivity of more than 80% and an 1xxx 1060, 1100, 1350 excellent reflector of radiant energy across the 2xxx 2011, 2014, 2024, 2219 full range of wavelengths, including ultra- 3xxx 3003, 3004 violet and infrared. 5xxx 5066, 5083, 5086, 5154, 5454, 5456 6xxx(a) 6005 (1962), 6005A, 6020, 6021, 6040, 6060 Good ductility and workability (due to the fcc (1972), 6061 (1935), 6063 (1944), 6066, 6070, structure) for fabrication by rolling, stamping, 6082 (1972), 6101 (1954), 6105 (1965), 6162, drawing, spinning, roll forming, forging, and 6262, 6351 (1958), 6463 (1957) extrusion. 7xxx 7001, 7003, 7004, 7005, 7029, 7046, 7050, 7075, Cryogenic toughness, as the fcc structure 7079, 7116, 7129, 7146, 7178 Examples of extruded sections produced does not become brittle at low temper- Fig. 1 (a) Year of introduction noted in parentheses for selected 6xxx series from easily extrudable aluminum alloys. alloys atures. Source: Ref 1 Extrusion of Aluminum Alloys / 523 alloy group due to its combination of material Extrudability of the moderately difficult or Profile Types characteristics, ease of extrusion, and econom- very difficult alloys also cannot be significantly ical production. increased by hot extrusion technology, because An extruded profile is defined as a product that Although the term extrudability (i.e., the of the narrow temperature interval between the is long in relation to its cross section other than material formability under conditions of the extrusion load limiting temperature and the extruded rod, wire, bar, tube, or pipe. Many extrusion process) does not have a precise phy- temperature of unacceptable surface quality. custom or complex cross-sectional designs are sical definition (see the section “Extrudability” Billet temperatures generally range from possible with aluminum extrusion and, as such, in this article), the relative extrudability of alu- approximately 300 to 595 C (575 to 1100 F), three broad categories of profiles have been minum alloys can be roughly ranked as measured depending on the alloy. Typical billet tempera- established: by extrusion exit speed, as given in handbook tures for some of the harder aluminum alloys are references for several of the more important listed in Table 3. This does not include variations Solid profiles: Extruded cross sections that do commercial extrusion alloys: in exit temperatures. For more information on not incorporate enclosed or partially enclosed hot extrusion of aluminum alloys, see the article voids (Some examples of solid profiles are Extrudability I-beams or C-channels; refer to Table 4 and Alloy (% of rate for 6063) “Conventional Hot Extrusion” in this Volume. Cold Extrusion. Aluminum alloys are well related information to discern solid from 1350 160 semihollow profiles.) 1060 135 adapted to cold (impact) extrusion. The lower- 1100 135 strength, more ductile alloys, such as 1100 and Hollow profiles: Extruded cross sections that 3003 120 3003, are the easiest to extrude. When higher contain one or more completely enclosed 6063 100 mechanical properties are required in the final voids in one or more portions of its overall 6061 60 shape geometry 2011 35 product, heat treatable grades are used. Although 5086 25 nearly all aluminum alloys can be cold extruded, Semihollow profiles: Extruded cross sections 2014 20 the five alloys most commonly used are: that contain one or more partially enclosed 5083 20 voids in one or more portions of its overall 2024 15 shape geometry (see also Table 5) 7075 9 Cold extrusion pressure Alloy relative to that for 7178 8 (annealed slug) 1100 aluminum 1100 1.0 In general, the higher the alloy content and 3003 1.2 strength, the greater the difficulty of extrusion 6061 1.6 Classes of Profiles and the lower the extrusion rate. The easily 2014 1.8 extruded alloys can be economically extruded at 7075 2.3 To further describe hollow and semihollow speeds up to 100 m/min (330 ft/min) or faster. profiles and to provide greater distinction from With a typical extrusion ratio of 40 to 1, exit For more information on cold extrusion of alu- solid type profiles, classes of profiles have been speeds of the more difficult alloys are on the minum alloys, see the article “Cold Extrusion” in defined for producers and users and are listed in order of 0.6 to 1.2 m/min (2 to 4 ft/min). this Volume. Table 4. Table 3 Typical values of billet temperature and extrusion speed of some harder aluminum alloys Table 2 Typical applications for 6xxx series aluminum extrusions Billet Temperature Exit speed Automobiles and other Air bag housings Alloy Type C F m/min ft/min ground transportation Automobile space frames 2014–2024 Heat treatable 420–450 788–842 1.5–3.5 5–11 Bumper components 5083, 5086, 5456 Non-heat-treatable 440–450 824–842 2–6 7–20 Engine mounts 7001 Heat treatable 370–415 700–780 0.5–1.5 2–5 Fuel-injection rails 7075, 7079 Heat treatable 300–460 572–860 0.8–2 3–7 Suspension components 7049, 7150, 7178 Heat treatable 300–440 572–824 0.8–1.8 2.5–6 Truck trailer frames Electrical and electronic Bus bar Note: Temperatures and extrusion speeds are dependent on the final shape and the extrusion ratio, and it may be necessary to start with lower billet components Cable trays temperatures than mentioned in the table. Source: Ref 1, 3 Electrical connectors Electrical shielding Heat sinks Household and architectural Appliance trim items Fencing Table 4 Hollow and semihollow profile classes Furniture Class Description Hand rails Lighting reflectors Hollow profiles Picture frames Shower curtain enclosures Class 1 Contains a single, round void that is equal to or greater than 25 mm (1 in.) in diameter and is Swimming pool structures symmetrical to its exterior geometry on two axes