Wrought Alloys - 5xxx Al-Mg Alloys
- Strain hardenable
- Excellent corrosion resistance,toughness,weldability; moderate strength
- Building & construction,automotive,cryogenic, marine applications
- Representative alloys:5052,5083,5754
- Typical ultimate tensile strength range:18-51 ksi
They are readily welded by a variety of techniques, even at thicknesses up to 20 cm. As a result, 5xxx alloys find wide application in building and construction, highways structures including bridges, storage tanks and pressure vessels, cryogenic tankage and systems for temperatures as low as -270°C (near absolute zero),and marine applications.
Alloys 5052, 5086,and 5083 are the work horses from the structural standpoint,with increasingly higher strength associated with the increasingly higher Mg content. Specialty alloys in the group include 5182,the beverage can end alloy, and thus among the largest in tonnage;5754 for automotive body panel and frame applications; and 5252,5457,and 5657 for bright trim applications, including automotive trim.
Care must be taken to avoid use of 5xxx alloys with more than 3% Mg content in applications where they receive continuous exposure to temperatures above 100°C (212°F). Such alloys may become sensitized and susceptible to stress corrosion cracking. For this reason, alloys such as 5454 and 5754 are recommended for applications where high temperature exposure is likely.
Examples of applications for the broadly used 5xxx series of alloys include:
- High speed single-hull ships like the Proserio employ 5083- H113/H321 machined plate for hulls,hull stiffeners,decking and superstructure.
- The internal hull stiffener structure of the high-speed yacht Proserio,from the previous figure.
- Single or multiple hull high-speed ferries, employ several Al-Mg alloys,5083,and 5454 as sheet and plate (along with 6xxx extruded shapes,to be described next) with all-welded construction.
- Alloy 5083 was the work horse for the 125-ft.diameter spheres for shipboard transport of liquefied natural gas;the all-welded construction was 8-in.thick at the horizontal diameter.
- The Foresmo bridge in northern Norway is an excellent example of the use of Al-Mg alloys for built up girders systems; this photo illustrates a major advantage of replacement aluminum bridges: the ability to pre-fabricate the spans and move them in place quickly, minimizing the disruption to traffic.
- Rugged coal cars are provided by welded 5454 alloy plate construction.
- The demands of high-humidity and water exposure in offshore oil rigs are met with 5454, 5086,and 5083 Al-Mg alloy welded construction.
- Automotive structures are likely to employ increasing amounts of 5754-0 formed sheet for parts such as internal door stiffeners or the entire body-in-white.
- Aluminum can ends of 5182 make that one of the largest volume alloys in production.