Identifying the Microstructural Basis for
Aluminum Alloy Formability
Brian M. Gable*
Mentor: Tim Foecke*
Category: Materials
NIST Center for Metal Forming, Metallurgy Division, MSEL
Room B254 / Building 223 / Mailstop 8553
Phone: 301-975-2033 / Fax: 301-975-4553
* Not a Sigma Xi member
Abstract
Aluminum alloys are attractive candidate materials for use in automobiles because of potential significant weight savings and concomitant improved fuel economy. Unfortunately, unpredictable forming limitations have hindered widespread implementation of aluminum alloy sheet. A primary concern is the insufficient strain-to-failure during traditional forming procedures. In many cases these limitations are exacerbated by the presence of non-uniform deformation structures, which are directly attributed to the size and distribution of the nano-scale phases utilized to strengthen the material. Our work involves characterizing the processing-microstructure-performance relationship of a candidate automotive aluminum alloy to better understand which microstructural features and deformation structures are deleterious and/or desirable for forming applications. Through the application of various artificial aging heat treatments, the precipitate structure, and hence the subsequent deformation structure, were altered and the strain-to-failure of different forming paths assessed. For equiaxial loading those specimens aged to create a more homogeneous deformation structure exhibited superior strain-to-failure over those intentionally aged to intensify non-uniform deformation.