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Micro-, Meso- and Macro-Texture and Fatigue Crack Roughness in Al-Li 2090 T8E41

Published online by Cambridge University Press:  10 February 2011

J. D. Haase ,
A. Guvenilir ,
J. R. Witt  and
S. R. Stock
J. D. Haase
Affiliation:
School of Materials Science and Engineering and Mechanical Properties Research Laboratory, Georgia Institute of Technology, Atlanta, GA 30332-0245
A. Guvenilir
Affiliation:
School of Materials Science and Engineering and Mechanical Properties Research Laboratory, Georgia Institute of Technology, Atlanta, GA 30332-0245
J. R. Witt
Affiliation:
School of Materials Science and Engineering and Mechanical Properties Research Laboratory, Georgia Institute of Technology, Atlanta, GA 30332-0245
S. R. Stock
Affiliation:
School of Materials Science and Engineering and Mechanical Properties Research Laboratory, Georgia Institute of Technology, Atlanta, GA 30332-0245
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Abstract

The use of synchrotron polychromatic x-ray microbeams in the transmission geometry is described for mapping grain orientation as a function of position and for relating this microtexture to the formation of large asperities on fatigue crack surfaces in Al-Li 2090 T8E41. In common with the centers of rolled plates of many aluminum alloys, Al-Li 2090 T8E41 has a sharp average texture or macrotexture different from that in the outer portions of the plate. The geometry of large asperities in Al-Li 2090 has been related to this macrotexture, and the resulting roughness-induced crack closure is recognized to be responsible for the very low crack propagation rates in certain plate orientations. This report focuses on why asperities form at certain positions and why the crack remains relatively planar elsewhere. The microtexture (i.e., the grain-to-grain orientation variation) seems to be organized into a specific type of mesotexture: multiple adjacent grains have nearly identical orientations and form substantial volumes of near-single-crystal material. Transitions between differently oriented near-singlecrystal volumes or between a near-single- crystal region and more randomly oriented grains appear to bound asperities.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 524: Symposium V – Application of Synchrotron Radiation Techniques…IV , 1998 , 37
Copyright
Copyright © Materials Research Society 1998

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