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

brian.gable@nist.gov

* 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.