Прегледај по Аутор "Petrović, Žarko"

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    EXPERIMENTAL VERIFICATION OF DIFFERENT THEORETICAL APPROACHES FOR DEFINING FLD
    (Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2014) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko
    Workability of materials is the possibility of permanent changes in shape and dimensions of workpieces without cracking or other forms of damage to the structure. This property, which numerically valorized by size of limit effective strain, depends on type of material, the initial structure and processing conditions. This paper shows results related to the defining of FLD in bulk metal forming processes, based on theapplication of various theoretical approaches for determining of mean values of ß – factor and strainlimit.
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    MORPHOLOGY OF STEEL C45E MICROSTRUCTURE DURING UPSETTING
    (Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2015) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko; Šljivić, Milan; Stefanović, Milentije
    Entirely understanding of all factors and mechanisms which influence nucleation and accumulation of ultimate level of material failure is necessary for adequate choice of material and rational projecting of metal forming technological procedure. The first step in research refers to the morphology characterization of material micro constituents during processing. This paper contains qualitative-quantitative analysis of morphology changes of ferrite and colonies of pearlite in the steel C45E microstructure during upsetting of cylindrical specimen with flat dies. Relative microforming level of ferrite grains was determined based on direct measurements, while indirect way has been suggested for determination of pearlite colonies forming ability. The approach is based on monitoring of area fraction changes of pearlite colonies in relation to area fraction of ferrite basis during upsetting process. The results of SEM testing have shown that ferrite grains and pearlite colonies are formed unequally.