Miniature tensile testing of SPD processed fine-grained aluminum

Harishchandra A. Lanjewar, Soroosh Naghdy, Leo A.I. Kestens, Patricia Verleysen

    Research output: Contribution to journalConference articleScientificpeer-review

    2 Citations (Scopus)
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    Manufacturing of ultrafine-grained (UFG) or nanocrystalline (NC) metals via a single step top-down approach imposing severe plastic deformation (SPD) is one of the most promising ways to achieve superior properties such as high strength and superplastic forming capability. Nonetheless, the lack of relevant data on their post-SPD performance in different test environments makes it difficult to fully understand their mechanical behavior. While characterizing the tensile behavior, almost all of the previous reports are limited to the discussion on the plastic performance of the material in terms of elongation to failure and corresponding strength, with only a few studies discussing the effect of grain fragmentation on work hardening response of the material. In the present work, a comprehensive analysis is presented in terms of the uniform and post-necking mechanical behavior of the ultrafine-grained material. Commercially pure aluminum is subjected to high pressure torsion (HPT) deformation with strains ranging from very low levels (γ ≈ 2.1) to values well in the saturation regime (γ ≈ 25.1). When tested in uniaxial tension, the strength increases monotonously. The uniform elongation improves with the imposed HPT strain, though remains lower than the value of the initial material. Based on the slopes of the stress-strain curve, three distinct zones are identified, i.e. uniform deformation, post-necking-1, and post-necking-2. With accumulating SPD deformation, the material shows enhanced pre-necking strength and ductility; while post-necking material fails early and at lower strength levels. The post-necking response is observed to be highly microstructure dependent: a lower grain size augments the resistance for micro-crack propagation and thus the ductility, however, once initiated, a crack propagates much faster in fine-grained than in coarse-grained HPT processed material.

    Original languageEnglish
    Article number012022
    Number of pages6
    JournalJournal of Physics: Conference Series
    Issue number1
    Publication statusPublished - 2019
    Event7th International Conference on Recrystallization and Grain Growth, ReX and GG 2019 - Ghent, Belgium
    Duration: 4 Aug 20199 Aug 2019


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