diplomsko delo
Jan Poklič (Author), Mitja Petrič (Mentor)

Abstract

Namen diplomskega dela je karakterizacija mikrostrukture sive litine s kroglastim grafitom kvalitete EN-GJS-400-18LT v odvisnosti od uporabljenega cepiva, načina cepljenja in debeline stene ulitka. Ulitih je bilo 6 ulitkov stopničaste oblike, z debelino sten 10, 20, 30, 40 in 50 mm. Uporabila so se štiri različna cepiva, in sicer na osnovi aluminija, barija, cirkonija in cerija. Cepiva z aluminijem, barijem in cirkonijem so se dodala pri prelivanju iz ponovce. Cepivo s cerijem se je dodalo talini cepljeni z barijem, in sicer enkrat v livno votlino in enkrat v curek pri ulivanju. En ulitek je bil ulit brez cepiva. Karakterizacija mikrostrukture je potekala s pomočjo svetlobne mikroskopije in programa AxioVision, določevanje kemijske sestave pa s pomočjo optične emisijske spektroskopije. Mirkostruktura litine EN-GJS-400-18LT je sestavljena iz feritno – perlitne matrice in ogljika izločenega v obliki grafitnih krogel. Pri vseh ulitkih se delež ferita pričakovano povečuje z debelino stene. Izkazalo se je, da cepivo z barijem učinkuje najslabše, saj je bilo število krogel najmanjše, delež ferita najmanjši, ulitek pa v najdebelejšem delu porozen. Cepivo z aluminijem je zagotovilo najbolj konstantno število in razporeditev krogel skozi celoten potek strjevanja a višji delež perlita napram ostalim cepivom. Cepivo s cirkonijem je v tanjšem delu ulitka poskrbelo za visoko število krogel, ki pa z debelino stene bistveno pade, je pa v tem primeru bistveno manj perlita že v najtanjši steni. Ulitku cepljenim z barijem in dodanim cepivom s cerijem v formo se število krogel le nekoliko povečalo in delež perlita nekoliko zmanjšal. Bistveno najboljše rezultate pa smo dosegli s cepivom z barijem in dodanim cepivom s cerijem v curek. Delež perlita je najmanjši, število krogel največje, le te pa so tudi najbolj pravilne pri vseh debelinah stene.

Keywords

siva litina s kroglastim grafitom;cepljenje;cepivo;mikrostruktura;grafit;debelina stene;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [J. Poklič]
UDC: 669
COBISS: 1841503 Link will open in a new window
Views: 710
Downloads: 174
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

Secondary language: English
Secondary title: influence of different inoculants and wall thicknesses on graphite size and distribution in ductile iron
Secondary abstract: The purpose of this diploma work is to examine the influence of different inoculants, methods of adding inoculants and casting wall thickness on microstructure of spheroidal cast iron type EN-GJS-400-18LT. 6 step shapped castings were made with wall thicknesess of 10, 20, 30, 40, and 50 mm. Four ferosilicon inoculants were used with the additions of aluminium, barium, zirconium and cerium. First three were added to the molten iron during pouring the liquid from one ladle to another. Inoculant with cerium was added to the barium treated iron, once in the mould and once in the stream. One casting was cast without any inoculant treatment. Microstructure examination was performed by light microscopy, while chemical analysis was performed by optical emission spectroscopy. EN-GJS-400-18LT has a ferritic, perlitic or ferittic-perliric matrix with embeded graphite nodules. Ferrite content gets higher with wall thickness, as we expected. We found out that inoculant with barium has the worst overall results. Nodule count and ferrite content were the lowest and the casting was porrous in the thickest section. Inoculant with added aluminium provided the most constant nodule count but higher pearlite content compared to other inoculants. Inoculant with zirconium provided hight nodule count and low pearlite content in the thinnest section, but failed to have the same effect in the thicker section. In mould inoculation using inoculant with cerium and pouring barium preinoculated iron gave a bit higher nodule count and ferrite content than using only inoculant with barium. The best results were obtained when inoculating barium treated iron in stream with cerium. Nodule count was the highest, nodule shape spherical throughout the whole casting and pealite content the lowest.
Secondary keywords: spehroidal cast iron;inoculation;inoculant;microstructure;graphite;wall thickness;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Odd. za materiale in metalurgijo
Pages: XII, 47 f.
ID: 11224164