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1.
Vpliv žarjenja za odpravo zaostalih napetosti na navarih zavarjenih po epp postopku
Žiga Tajnikar, 2018, master's thesis

Abstract: Magistrsko delo obravnava vpliv žarjenja za odpravo zaostalih napetosti na navarih, zavarjenih po postopku EPP. Za raziskavo so bili izdelani preizkušanci z navari, med katerimi so bili trije preizkušanci izpostavljeni različnim temperaturam žarjenja in četrti preizkušanec, ki je ostal v varjenem stanju brez žarjenja za odpravo zaostalih napetosti. Na preizkušancih je bila izmerjena stopnja deformacije s koordinatno merilno napravo in zaostale napetosti z magnetno metodo. Meritve so pokazale, da ima višina temperature žarenja pomemben vpliv na velikost zaostalih napetosti in stopnjo deformacije na preizkušancih. Ugotovljeno je bilo, da učinkovitost žarjenja s temperaturo narašča le do maksimalne temperature, ki je odvisna od izbranega osnovnega in dodajnega materiala. Z nadaljnjim zvišanjem temperature se učinkovitost žarjenja ponovno zmanjša.
Keywords: varjenje, postopek EPP, zaostale napetosti, deformacija
Published: 09.02.2018; Views: 661; Downloads: 75
.pdf Full text (6,08 MB)

2.
Metalografska preiskava nosilca žiga
Tomi Kenda, 2017, undergraduate thesis

Abstract: V podjetju GKN Driveline Slovenija prihaja do težav pri izdelavi kletk ležajev za homokinetični zglob, in sicer pri prebijanju okenc na kletki, v katero so vstavljene ležajne kroglice. V podjetju želijo zagotoviti daljšo življenjsko dobo nosilca orodja za prebijanje in so se odločili v prvi fazi preiskati ali je uporabljen predpisani material in/ali je toplotno obdelan kot predvideva tehniška dokumentacija. Naloga zajema pregled prelomnih površin, kemijsko analizo, preiskavo mikrostrukture in merjenje trdote. Vse preiskave so privedle do ugotovitve, da sta material in toplotna obdelava materiala v skladu s tehniško dokumentacijo. Rešitev je potrebno zato poiskati bodisi v drugem materialu, drugačni obdelavi ali v spremembi konstrukcije nosilca.
Keywords: GKN, Nosilec žiga, Metalografska preiskava, Meritve trdote
Published: 10.11.2017; Views: 532; Downloads: 59
.pdf Full text (3,87 MB)

3.
Synthesis and characterization of hardened Cu-Fe-Ni-P alloy
Goran Brovč, Goran Dražić, Blaž Karpe, Igor Đorđević, Gorazd Lojen, Borut Kosec, Milan Bizjak, 2015, original scientific article

Abstract: In the manufacturing industry of electrical contacts, the prohibition of the use of toxic metals (Cd, Be), and desire to avoid the alloying with precious metals (Ag) has created a need for new alloys with good electrical conductivity and high mechanical properties at elevated temperatures. As a potentially useful material for this purpose, we have analyzed the continuously cast Cu-Fe-Ni-P alloy in various heat treatment conditions. Sequence of phase transformations during heat treatment was followed by 4 point D.C. electrical resistivity measuring method, and analyzed by scanning (SEM) and transmission (TEM) electron microscopy. Measurements of Vickers hardness and electrical conductivity after various heat treatment procedures indicate on high potential of Cu-Fe-Ni-P alloys as a material for electrical contacts.
Keywords: copper alloys, precipitation hardening, electrical contacts, electrical conductivity
Published: 03.07.2017; Views: 1545; Downloads: 73
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4.
Microstructural and phase analysis of CuAlNi shape-memory alloy after continuous casting
Mirko Gojić, Stjepan Kožuh, Ivan Anžel, Gorazd Lojen, Ivana Ivanić, Borut Kosec, 2013, original scientific article

Abstract: The results of the characterization of a CuAlNi shape-memory alloy after continuous casting technology are shown. Using this procedure a bar with a diameter of 8 mm was manufactured. After solidification of the alloy the microstructure characterization was carried out using optic microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. Our results showed that the as-cast alloy consisted of the parent β1 and β1’ martensite phases. The martensite phase primary as the needle-like inside grains was observed. Martensite laths have different orientations inside particular grains. It was found that the average grains size is 98.78 µm. The grain diameter near to the external surface is higher than in the center. The average hardness of the alloy was 275 HV1.
Keywords: shape memory alloys, martensite, continuous casting, grain size
Published: 16.03.2017; Views: 583; Downloads: 77
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5.
Continuous vertical casting of a NiTi alloy
Aleš Stambolić, Ivan Anžel, Gorazd Lojen, Aleksandra Kocijan, Monika Jenko, Rebeka Rudolf, 2016, original scientific article

Abstract: In this paper we present research that is connected to the performance of a series of experiments combined with the vacuum-induction melting and continuous vertical casting of a NiTi alloy in order to produce the strand. The theoretical chosen parameters made it possible to obtain a continuously cast strand with a diameter of 11 mm. The strand microstructures were investigated with a light and scanning electron microscope, while the chemical composition of the single phase was identified with the semi-quantitative micro-analysis energy-dispersive X-ray spectroscopy and inductively coupled plasma – optical emission spectrometry. The research showed that the microstructure is dendritic, where in the inter-dendritic region the eutectic is composed of a dark NiTi phase and a bright TiNi3–x phase. In some areas we found Ti carbides and phases rich in Fe. The micro-chemical analysis of the NiTi strand showed that the composition changed over the cross and longitudinal sections, which is proof that the as-cast alloys are inhomogeneous. In the final part, the electrochemical behaviours of NiTi strand samples were compared to a commercially available NiTi cast alloy with the same composition.
Keywords: NiTi alloy, continuous vertical casting, microstructure, potentiodynamic and impedance test
Published: 14.03.2017; Views: 780; Downloads: 284
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6.
Karakterizacija učinkov spremembe načina cepljenja na mehanske in mikrostrukturne lastnosti sive litine s kroglastim grafitom
Aljoša Zalokar, 2016, undergraduate thesis

Abstract: V diplomskem delu obravnavamo učinke prehoda z enostopenjskega na dvostopenjsko cepljenje na mikrostrukturne in mehanske lastnosti sive litine s kroglastim grafitom. Cilj spremembe je bil zmanjšati količino porabljenih cepiv in na ta način zagotoviti stroškovno učinkovitejšo proizvodnjo ob istočasni ohranitvi mikrostrukturnih in mehanskih lastnosti. Mikrostrukturne lastnosti smo ugotavljali z optično metalografsko analizo in avtomatično grafično analizo grafita. Mehanske lastnosti smo ugotavljali z nateznim preizkusom. Dobljeni rezultati so pokazali, da pri spremembi na dvostopenjsko cepljenje kljub manjši porabi cepiva mikrostrukturne in mehanske lastnosti ne odstopajo od obstoječih lastnosti, pridobljenih z enostopenjskim načinom cepljenja. Predpostavka, da lahko ob prehodu na dvostopenjsko cepljenje zmanjšamo porabljeno količino cepiva ob istočasni ohranitvi mikrostrukturnih in mehanskih lastnosti, je bila v diplomskem delu potrjena.
Keywords: siva litina, kroglasti grafit, cepljenje, mikrostrukturne lastnosti, mehanske lastnosti
Published: 19.10.2016; Views: 911; Downloads: 92
.pdf Full text (6,48 MB)

7.
Določitev temperaturnega procesnega okna za kovanje vijakov iz nerjavnega jekla
Gregor Ortl, 2016, undergraduate thesis

Abstract: Diplomsko delo zajema področje vročega kovanja cilindričnih vijakov z notranjim vtiskom (inbus) iz nerjavnega jekla. Predstavljen je sodoben način izdelave vijakov, kjer je podrobno opisan načrt raziskave. Zbrani in ovrednoteni so podatki meritev temperatur surovcev za kovanje, narejeni so natezni preskusi vijakov in določeni sta temperaturni procesni okni za enostopenjsko oziroma dvostopenjsko kovanje. Prikazane so tudi simulacije kovanja in metalografske preiskave.
Keywords: vijak, temperatura kovanja, nerjavno jeklo, natezni preskus, mikrostruktura.
Published: 23.09.2016; Views: 970; Downloads: 117
.pdf Full text (4,32 MB)

8.
IZDELAVA GRAFIČNEGA VMESNIKA ZA AVTOMATIZACIJO VLAČENJA PALICE PRI KONTINUIRNEM LITJU
Matevž Lešnik, 2016, undergraduate thesis

Abstract: V diplomskem delu je opisan postopek in metode kontinuirnega litja ter zahteve vodenja, ki jih moramo doseči ob pravilnem delovanju sistema. Preučili smo programsko opremo za izdelavo grafičnega vmesnika in programsko opremo za izdelavo nadzornega programa, ki skrbi za pravilno delovanje sistema. V ta namen je bil izdelan testni model programirljivega logičnega krmilnika z motorjem, grafični vmesnik in nadzorni program. Sledilo je tudi testiranje pravilnega delovanja sistema na testnem modelu.
Keywords: kontinuirno litje, avtomatizacija, grafični vmesnik, SCADA, PLK
Published: 06.09.2016; Views: 512; Downloads: 44
.pdf Full text (2,86 MB)

9.
Učni načrte
Niko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, Bojan Bučar, 2010, dictionary, encyclopaedia, lexicon, manual, atlas, map

Keywords: srednje šole, učni programi, vaje za srednje šole
Published: 21.12.2015; Views: 528; Downloads: 18
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10.
Učni načrt
Niko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, 2010, dictionary, encyclopaedia, lexicon, manual, atlas, map

Keywords: srednje šole, učni programi
Published: 21.12.2015; Views: 675; Downloads: 10
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