Linking Porosity to Rolling Reduction and Fatigue Lifetime of Hot Rolled AA7xxx Alloys by 3D X-Ray Computed Tomography

Authors

  • Xiaomin Wu,

    Corresponding author
    1. Material Innovation Institute (M2i), Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands
    • Material Innovation Institute (M2i), Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands.
    Search for more papers by this author
  • Erik Schlangen,

    1. Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands
    Search for more papers by this author
  • Sybrand van der Zwaag

    1. Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands
    Search for more papers by this author

  • This research was carried out under the project numbers M41.10.08322 in the framework of the Research Program of the Materials innovation institute (www.m2i.nl). Support and technical discussions with Arjan Thijssen, Wim Verwaal, and Jos van Meel (Faculty of Civil Engineering and Geosciences, Delft University of Technology) are appreciated.

Abstract

A set of hot rolled 7xxx aluminum alloys with different casting conditions and modification of processing conditions were analyzed on their fatigue life time as well as the internal microstructure using 3D computed X-ray tomography with a lab scale scanner and optical microscopy. It is shown that large retained casting pores exist in samples with low reduction rate. The modification on the hot rolling process is now proved to be much more effective on removing large casting pores in the alloy. It is also found that with the improved casting conditions and the additional deformation imposed by increased rolling reduction, this advantage is getting retarded. The combination of porosity analysis with low cycle fatigue test at peak stress of 300 MPa indicates that reduction of the size of large pores in the sample down to 10 µm will lead to greatly improved fatigue life times.

Ancillary