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Microstructural features evaluation of age-hardened A 226 cast alloy by image analysis

Kucharikova L., Tillova E.

Production Engineering Archives

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2017

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Vol. 17

3--8

EN

Age-hardening provides one of the most widely used mechanisms for the strengthening of aluminum alloys. The age-hardening involves three steps: solution treatment, quenching and aging. The temperature of solution treatment and aging is very important in order to reach desired properties of castings. The optimum temperature of solution treatment and aging led to formation microstructural features in form which does not lead to decreasing properties, but increasing ones. The major micro-structural features in A 226 cast alloys which are responsible for increasing properties are: eutectic Si particles, Cu-rich phases, Fe-rich phases and porosity. The increase of properties depends on morphology, size and volume of microstructural features. In order to assess age-hardening influence on microstructural features in A226 cast alloys were used as possibilities of evaluation by means of image analysis. Quantitative analysis decelerate changes in microstructure includes the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu) further increase in the hardness and tensile strength in the alloy. Changes of mechanical properties were measured in line with STN EN ISO.

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On the mechanical properties and structure of age-hardened AlSi9Cu3 cast alloy

Hurtalova L., Tillova E.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 2

355-362

EN

The paper describes the influence of age-hardening by solution treatment at 515 C with holding time 4 hours, water quenching at 40 C and artificial aging at different temperature 130 C, 150 C and 170 C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (strength tensile and Brinell hardness) and changes in the morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled) AlSi9Cu3 cast alloy. The structure with of black-white etching was observed (Dix-Keller, H2SO4). A quantitative study of changes in the morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. The analysis of intermetallic phases was performed on SEM using EDX. Mechanical properties were measured in line with STN EN ISO. Age-hardening led to changes in the microstructure including spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu), further increase in the hardness and tensile strength in the alloy.

3

Influence of the ageing on mechanical properties of the aluminium alloy AlSi9Mg

Dobrzański L., Reimann Ł., Krawczyk G.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

37-40

EN

Purpose: The goal of this paper was study the influence of temperature and time in the age-hardening on the selected mechanical properties and hardness of the AlSi9Mg alloy. Design/methodology/approach: The efficiency of the age-hardening were tested on laboratory specimens through the statically tension test on ZWICK/Z100. Damages were critically assessed through SEM investigations. Evaluation the mechanical properties of prepared samples were realized by solutioning and then ageing in different periods of time. Findings: Adequately selected time of the ageing improved the hardening and plasticity and reduce the tendency of aluminium to formation of coagulations. Research limitations/implications: The described investigations were limited to changes the mechanical properties of the specimens in different periods of time of aging, in solid temprature. In future research works should show the influence of change of temperature process on studied AlSi9Mg alloy, as well as different lightweight alloy. Originality/value: The paper contributes to better understanding and recognition the mechanisms of agehardening.