Browsing by Subject "aging"

Now showing 1 - 3 of 3

Access status: Open Access ,
Effect of additional alloying and heat treatment on phase composition and morphology in Al-Mg-Si-type casting alloy
(Wydawnictwa AGH, 2017) Bojko, Vìctorìâ; Czekaj, Edward; Warmuzek, Małgorzata; Mihalenkov, Kostântin Vìktoroviĉ
The structure of permanent mold and high pressure die castings of the AlMg5Si2Mn alloy after alloying with Li and Sc has been investigated by scanning and transmission electron microscopy, hardness and microhardness measurements, energy dispersive X-ray analysis. Three conditions, as cast, solution treated and aged, were investigated. It was shown that in as-cast state, the structure of an alloy having the nominal composition AlMg5Si2Mn consists of four phases: first - the Al based solid solution, second - the (Al) + (Mg?Si) eutectic, third - the primary Mg?Si crystals and fourth - the a-Al(Mn, Fe)Si phase. Similar phases were observed in the alloys containing Sc or Li. After two days of storing in an as-cast condition, the solid solution in all tested alloys decomposes and forms zebra-crossing shaped precipitates. TEM examinations revealed that these precipitates nucleate heterogeneously on dislocations. The solution treatment at 575.0°C results in spheroidization of the Mg2Si lamellas, dissolution of the precipitates and formation of a-Al(Mn, Fe)Si dispersoids, nucleating on the surfaces of Mg?Si lamellas. In the Sc containing alloys, the formation of Al?Sc was detected after 120 min soaking. Further heating resulted in the growth of these precipitates. Aging of the Al-Mg-Si alloys leads to an increase of hardness in all studied alloys. This effect is mainly related to precipitation strengthening, via solid solution decomposition and formation of b''-phase. In Li-alloyed specimens, plates of b Mg?Si phase were observed together with small cubic-shaped d' Al?Li precipitates.
Access status: Open Access ,
Praktyka grania wśród graczy 50+ w perspektywie etnografii wirtualnej
(Wydawnictwa AGH, 2019) Gałuszka, Damian
In this paper, the phenomena of gaming among mature and older people is presented. For the purpose of the main subject of the paper, virtual ethnography research was conducted in 2017, covering two important Internet forums for gamers aged 25 and over: The Older Gamers (TOG) and Senior Gamers (SG). In total, a set of 471 posts was coded, resulting in an in-depth description of five relevant aspects of gaming practice among gamers aged 50+: the general category that consists of basic user traits, their gaming habits, the hardware used to play games, their competences and knowledge related to games and gained during gaming sessions and the role of social environment, especially family. This study is not only novel in that it utilizes the virtual ethnographic approach to the topic of gaming among older and senior people, but also starts a discussion on these phenomena in Polish academic discourse.
Access status: Open Access ,
The influence of aging on buckle strength loss in AA5182-H48 for beverage can ends
(Wydawnictwa AGH, 2023) Kokoszka, Paweł; Milenin, Andriy
The paper examines the influence of aging on buckling strength loss for aluminum alloy 5182 beverage can ends. In the experimental study, aging took place naturally and artificially. For the buckling strength testing, a special experimental technique was used, which was based on measuring the internal pressure leading to the destruction of the beverage can ends. The experimental results show that the beverage can ends indicate a significant time-dependent buckle strength loss. For example, a year of aging can end at 20°C leading to a decrease in its strength by 5%. Half of this decrease occurs in the first 3–4 weeks. The aging phenomenon also got worse with increasing temperature. It has been found that increasing the aging temperature to 40°C results in an 8% reduction in buckling strength after 4 weeks of aging. The whole life cycle, from its production to the processes it undergoes and storage time, was analyzed. At the same time, tests were carried out for both the input material and the product itself. On this basis, the mechanical properties and their change depending on time or temperature were examined. All specimens made from can end stock (CES) were also found to not show the same drop of mechanical properties as for the buckling of finished ends. The obtained experimental allowed the development of an empirical mathematical model that makes it possible to predict the buckling strength of the can end depending on the conditions of aging and temperature of testing. The present study showed the importance of temperature conditions used in can filling lines in the determination of resistance to changes in buckling for the ends.