Прегледај по Аутор "Mitić, Dragan"

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    DISSIMILAR WELDING OF ALUMINUM ALLOYS 2024 T351 AND 6082 T6 BY TIG PROCESS
    (Sveučilište u Slavonskom Brodu, Strojarski fakultet, Društvo za tehniku zavarivanja Slavonski Brod, 2023) Milčić, Dragan; Milčić, Miodrag; Vuherer, Tomaž; Đurić, Aleksija; Mitić, Dragan; Radovanović, Andreja
    The aim of this work is to study the metallurgical and mechanical properties of dissimilar assemblies of 2024 T351 and 6082 T6 aluminum alloy by the TIG process. Aluminum alloy 6082 T6 is well weldable by classical fusion welding processes (MIG and TIG), while aluminum alloy 2024-T351 is almost non-weldable. Base metals were sheets with a thickness of 8 mm. The assembly of the plates was carried out by filler wire of an aluminum alloy type 4043A (AlSi5) with 2 mm of diameter. For the welding of these two Al alloys by TIG welding process in argon a shielding gas. The microstructural evolution across the welded joint dissimilar AA6082-T6 to AA2024-T351 aluminum alloy was characterized using optical and scanning electron microscopy (SEM). The hardness welded joint is the smallest in the melted area and the biggest on the side of 2024 alloy in HAZ. The fracture surface section of the tensile specimen is in the HAZ zone on the BM side - 6082-T6. The tensile strength of the welded joint is 166 MPa compared to 310 MPa for alloy 6082-T6 which is a weaker welded joint material, i.e. the reduction is about two times.
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    KARAKTERIZACIJA ZAVARENIH SPOJEVA SA DELIMIČNOM PENETRACIJOM NA KONSTRUKCIONOM ČELIKU S355N
    (DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd, 2021) Milčić, Dragan; Mitić, Dragan; Radović, Nenad; Milčić, Miodrag; Đurić, Aleksija; Antić, Milica
    Postojeći standardi zahtevaju zavarene spojeve sa potpunom penetracijom. Smatra se, da se zavarenim spojevima sa potpunom penetracijom, minimizira koncentracija napona u korenskom prolazu. Međutim, brojne su situacije u industriji, u kojima je zadovoljavajuća nosivost zavarenog spoja sa delimičnom penetracijom. Ako ispitivanja zavarenih spojeva sa delimičnom penetracijom pokažu zadovoljavajuću nosivost, benefiti u odnosu na zavarene spojeve sa potpunom penetracijom se ogledaju u nižim troškovima, odnosno manje je potrebno vreme za pripremu spoja, manje je potrebno dodatnog materijala, odnosno kraće je vreme neophodno za izradu zavarenog spoja. U radu je dato ispitivanje sučeonih zavarivanih spojeva konstrukcionog čelika S355N, sa delimičnom penetracijom, ostvarenih MAG postupkom u nadglavnom položaju (PD) u zaštiti mešavine gasova. Uzorci su zavarivani sa različitim parametrima zavarivanja i sa različitom pripremom spoja – dubina spoja, a ispitivanja su vršena nedestruktivnim metodama (vizuelna kontrola, ispitivanje penetrantima i magnetnim česticama) i destruktivnim metodama –zatezanje, savijanje i tvrdoća.
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    RESISTANCE SPOT WELDING OF STEEL SHEET DP500 - INFLUENCE OF THE WELDING CURRENT ON THE MICROHARDNESS AND WELD NUGGET DIAMETER
    (Sveučilište u Slavonskom Brodu, Strojarski fakultet, 2021) Đurić, Aleksija; Milčić, Dragan; Marković, Biljana; Klobčar, Damjan; Milčić, Miodrag; Mitić, Dragan
    Dual-Phase steel has been used in body-in-white in order to reduce the weight and enhance the safety of automobiles. One of the most used technology for joining steel in automotive industry is Resistance spot welding. This paper presnet the analysis of the welding current influence on the microhardness and weld nugget diameter. It will be shown in the paper that the increased hardness of the fusion zones reduces the possibility of the necking in the base metal (i. e. Pull-out Fracture - PF mode), which is not considered as a favorable case.Specimens welded with current of 8 kA showed the best mechanical characteristics, the failure load was approximately 20000 N, the hardness of the fusion zone was approximately 350 HV and during the tensile-shear test they faile in PF mode.