Investigation of the Possibility for Compensating the HAZ Softening of AA7075-T6

New generations of high strength aluminum alloys are increasingly used in automotive industry. AA7075 is one of the strongest aluminum alloys in industrial use today. The outstanding strength properties open the possibility to use this alloy in automotive industry as a possible alternative material for car body elements instead of steels. Growing industrial demand of aluminum alloys led to the development new technologies, processes. Solution heat treatment, forming, and in-die quenching is one such technology. In our research work the different parts of the heat affected zone of AA7075-T6 high strength aluminum were examined. The thermal cycle of the heat affected zone was tested at four different temperatures (280 °C, 380 °C, 440 °C, 550 °C) with the help of physical simulation. The aim was to define the softening tendency of the heat affected zone after gas tungsten arc welding. Two heat input values 100 J/mm and 200 J/mm were selected in order to simulate a low and a high heat input welding at the given sheet thickness and welding technology by the application of Rykalin 2D model. Then the most critical subzone was selected for the further investigations. Therefore, the 380 °C temperature was examined in case of five more technical processes, which based on the solution heat treatment, forming, and in-die quenching process. The properties of the investigated subzone were examined by optical microscope and hardness test

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

The energy consumption of mechanical ventilation in buildings needs to be reduced. An efficient way to achieve this goal is to reduce the hydraulic resistance of the ventilation duct system elements, for example, that of sudden expansions. Ventilation ducts and pipe fittings are frequently of rectangular cross-section. The present paper investigates a passive flow control method in order to reduce the loss coefficient of a square-to-square sudden expansion, where the loss-reducing appendages are short guide vanes, termed as miniflaps, placed at the step edge of the sudden expansion. The turbulent flow is examined numerically using the generalized k-ω model of the Ansys Fluent software for different area ratios of the sudden expansion, miniflap lengths, and miniflap angle setups. The Reynolds number is kept constant at 1.08·105. Based on the results of the numerical simulations, the loss coefficient of the sudden expansion can be reduced by ~20–25% for an optimum miniflap angle between 9° and 12°. Increasing the length of the miniflaps leads to a greater reduction of the loss coefficient up to a miniflap length of 0.3 dh1, where dh1 is the upstream hydraulic diameter of the duct

Foreword- Prof. Dr. Lukács János, Editor-in-Chief

I have often wondered whether we should have a Foreword in our journal, because as the saying goes, good wine does not need a label. Finally, as you can see, I thought that it might not be superfluous to preface this issue with an enthusiastic introduction, summarising the essence of the many articles in it, sharing my feelings and experiences of reading them, and presenting the general lessons of the research results written with professional thoroughnes

Előszó - Prof. Dr. Lukács János, főszerkesztő

Azzal, hogy az Állami Számvevőszék átadta a Pénzügyi Szemle alapítói és laptulajdonosi jogát a Budapesti Corvinus Egyetemnek, egy évtizedek óta dédelgetett álma valósult meg a pénzügyi, pénzügy jogi, számviteli és ellenőrzési területen kutatóknak, oktatóknak és gyakorlati szakembereknek

Előszó – Prof. Dr. Lukács János, főszerkesztő

Sokat gondolkodtam azon, hogy szükség van-e folyóiratunkban az Előszóra, hiszen a jó bornak sem kell cégér. Végül – mint ahogy az látható – arra jutottam, hogy talán nem fölösleges, hogy elöljáróban lelkesen beharangozzam, összefoglaljam egy új lapszám sokszínű cikkeinek lényegét, megosszam azok elolvasása okozta érzéseimet, élményeimet, bemutassam a szakmai alapossággal írt tanulmányok, kutatási eredmények általános tanulságait

Prof. Dr. Lukács János, Editor-in-Chief

With the transfer of the ownership of the Public Finance Quarterly from the State Audit Office of Hungary to Corvinus University of Budapest, a dream that has been cherished for decades by researchers, academics, and practitioners in the fields of finance, financial law, accounting, and auditing has finally been realized