The interest in aluminum alloys and aluminum joining in the automotive industry has increased considerably over the past few years as a result of new fuel economy, air pollution and safety requirements. Aluminum is the best alternative to steel to make lighter and more fuel-efficient automobiles. Several aluminum alloys have been considered for body sheet components. The new Alcoa 6009-T4 and 6010-T4 alloys were developed and introduced in 1976 to increase the attractiveness of aluminum for body sheet components. These alloys have good formability in the as-received condition and superior strength and dent resistance in the aged (-T6) condition which can be achieved in paint bake cycles. These alloys are similar in composition and do not require scrap segregation. In addition, the 6009/6010 alloys provide improved welding characteristics through a combination of better metallurgical characteristics and lower and more uniform surface resistance. This paper discusses the metallurgical factors and surface conditions which make these new alloys better performers. It also discusses applicable joining methods, procedures and the test results obtained.
