Metallurgical Abstracts on Light Metals and Alloys vol.55

Significant Bauschinger effect and back stress strengthening in an ultrafine grained pure aluminum fabricated by severe plastic deformation process

Si Gao1, Kota Yoshino1, Daisuke Terada2, Yoshihisa Kaneko3 and Nobuhiro Tsuji1,4
1Department of Materials Science and Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
2Dept. Mechanical Science and Engineering, Chiba Institute of Technology, Japan
3Department of Mechanical Engineering, Osaka City University, Osaka, Japan
4Elements Strategy Initiative for Structural Materials (ESISM), Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan

[Published in Scripta Materialia, Vol. 211 (2022), 114503]

https://doi.org/10.1016/j.scriptamat.2022.114503
E-mail: nobuhiro-tsuji[at]mtl.kyoto-u.ac.jp
Key Words: Mechanical properties, Bauschinger effect, Back stress, Ultrafine-grained materials

Bauschinger test in uniaxial tension-compression mode was carried out for the first time on the pure Al specimens having homogeneous ultra-fine grained (UFG) microstructures fabricated by equal-channel angular pressing (ECAP) and subsequent annealing processes. Significant Bauschinger stress (transient softening), Bauschinger energy parameter and their strong dependences on the tensile plastic pre-strain at the very early stage of the tensile deformation were measured in the UFG specimens, in sharp contrast to their coarse-grained (CG) counterpart. The grain size dependence of the Bauschinger effect in pure Al was qualitatively discussed in terms of the back stress arising from the formation of dislocation pile-up against the grain boundary during plastic deformation.

Stress-strain curves of monotonic tensile test on three grain sizes (a) and Bauschinger test on UFG-1 (b), UFG-2 (c) and CG (d) specimen.