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2 2015

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Impact of rotary swaging and age hardening on mechanical properties of EN AW 2024

Kövér M., Sláma P., Palán J.

Journal of Achievements in Materials and Manufacturing Engineering

2015

Vol. 72, nr 2

61--66

Purpose: Invention of severe plastic deformation methods led to increased interest in ultra-fine grained materials. The hardenable aluminium alloys were extensively studied in the last decade. It was revealed that combination of severe plastic deformation and age hardening can significantly improve the material properties of these alloys. In this article we performed such progressive thermo-mechanical treatment and following mechanical testing and metallographic analysis. The aim was to evaluate the influence of this treatment on mechanical properties, mostly the effect of various age hardening temperatures and time. Aluminium alloy EN AW 2024 was chosen for the experimental procedures. Impact of processing parameters on mechanical properties was determined by tensile testing. Metallographic analysis was used for evaluation of the straining influence on grain morphology. In the conclusion we denoted significant strain hardening effect, present shear bands and change in aging kinetics. Design/methodology/approach: The experimental material was processed by progressive thermo-mechanical treatment. The evaluation was performed by simple tensile testing and light microscopy. The first conclusions were derived from determined mechanical properties and based on similarities in available publications with related topic. Findings: The research results roughly confirm the recovery-precipitation complementary effect, observed in other hardenable aluminium alloys or the same hardenable alloy deformed by other SPD technique. The impact of both parts of processing – deformation and age hardening on mechanical properties was evaluated. Research limitations/implications: Future detailed investigation of secondary phase particles and dislocation-precipitate interaction should be performed. This investigation was not performed as it requires transmission electron microscopy. Originality/value: The paper contains first impression on promising SPD technique. As the technique appeared only recently, very few articles were published, considering few light alloys. The paper can help to set parameters for other researchers in this field and promote commercialization of this progressive thermo-mechanical processing

Miniature specimen tensile testing of AZ31 alloy processed by ECAP

Procházka R., Džugan J., Kövér M.

Archives of Materials Science and Engineering

2015

Vol. 76, nr 2

134--139

Purpose: Evaluation of bulk nanomaterials and ultra-fine grain structures consists mostly of metallographic evaluation and hardness measurement. The documentation of mechanical properties by hardness testing only might be very inaccurate due to the measurement error and sensitivity. Moreover the yield stress, ultimate tensile stress an elongation determined by tensile testing are more suitable for description of mechanical properties. This article promotes miniature tensile testing. Although the miniature tensile testing could be commonly used for description of mechanical properties in SPD materials, it is quite unknown. Design/methodology/approach: In this article the miniature tensile testing was used for determination. of mechanical properties anisotropy in AZ31 alloy processed by ECAP. The verification was performed by comparison of conventional and miniature tensile specimens of the non-deformed bulk material. Findings: From the experimental procedure and results low material consumption during sampling, sampling and measurement simplicity and possibility to measure the properties in various directions are denoted. Research limitations/implications: Future detailed investigation of secondary phase particles and dislocation-precipitate interaction should be performed. This investigation was not performed as it requires transmission electron microscopy. Such investigation will be performed only for chosen specimens to confirm discussed hypotheses. Practical implications: The paper promotes application of miniature tensile testing for determination of mechanical properties in SPD processed materials. Application of this methodology allows determination of mechanical properties from local volume, material save or preformation of several experiments from a single specimen. Originality/value: The finding might be valuable for researchers in SPD field. The originality of this paper is based on novel methodology and its applicability.