The need to reduce emissions while enhancing performance and adding fea-tures has driven manufacturers to use more aluminum in automobiles andlight trucks. This effort has been accompanied by the development of newaluminum alloys specically tailored for these applications. Many of thesealloys are too new to be listed in ASTM specications or Aluminum Standardsand Data, so detailed information is given here.
Since automobiles and light trucks undergo a paint-bake cycle at temperatureshigh enough to affect the temper of both heat-treatable and non-heattreatablealuminum alloys, the automotive alloys are provided in the -T4(solution-heat-treated) and -O (annealed) tempers, respectively. Both have thebest formability in these tempers for the cold-working they undergo in theprocess of being formed into body panels (6). The forming operation increasesstrengths through cold-working.
The subsequent paint bake articially agesthe heat-treatable alloys, which can additionally increase their strength, butre-anneals the non-heat-treatable alloys, erasing any strength increase due tocold work.
High strength is not necessarily important in this application,however.The automotive alloys fall in three groups: 2xxx series (aluminum-copper alloys), including 2008, 2010, and 2036.Alloys 2008 and 2010 were developed to provide improved formabilityover 2036. Alloy 2036 has more copper than 2008 and 2010, giving itabout 40% higher strength but less corrosion resistance. These alloys areheat-treatable.
5xxx series (aluminum-magnesium alloys), including 5182 and 5754.5182 was developed for the ends of beverage cans. It has a high magnesiumcontent, providing high strength but also sensitivity to corrosionwhen exposed to temperatures above 150F for extended periods.
5754is a variant on 5454, with slightly more magnesium (3.1% versus 2.7%)and lower strength, but better formability.6xxx series (aluminum-magnesium-silicon alloys), including 6009, 6111,and 6022. These alloys are heat-treatable and can attain fairly high.The automotive alloys fall in three groups: 2xxx series (aluminum-copper alloys), including 2008, 2010, and 2036.Alloys 2008 and 2010 were developed to provide improved formabilityover 2036. Alloy 2036 has more copper than 2008 and 2010, giving itabout 40% higher strength but less corrosion resistance. These alloys areheat-treatable.
5xxx series (aluminum-magnesium alloys), including 5182 and 5754.5182 was developed for the ends of beverage cans. It has a high magnesiumcontent, providing high strength but also sensitivity to corrosionwhen exposed to temperatures above 150F for extended periods. 5754is a variant on 5454, with slightly more magnesium (3.1% versus 2.7%)and lower strength, but better formability.6xxx series (aluminum-magnesium-silicon alloys), including 6009, 6111,and 6022. These alloys are heat-treatable and can attain fairly high.
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