Karakterizacija napak na ulitku iz sive litine s kroglastim grafitom

Cizej, Jure (author), Mrvar, Primož (mentor), Petrič, Mitja (co-mentor)

V metalurgiji je sestava preučevanega materiala pomembna za nadaljnje raziskovanje. Ravno zato sem v pričujočem delu ugotavljal lastnosti sive litine, saj je ta ena izmed najbolj razširjenih skupin materialov. V ta namen sem uporabil diferenčno vrstično kalorimetrijo (DSC), pri kateri sem ugotovil temperaturno področje transformacije. Namen diplomskega dela je bil analizirati tudi mikrostrukturo sive litine s kroglastim grafitom. Ta preizkus sem opravil z optično mikroskopijo, kjer sem analiziral obliko, velikost in porazdelitev grafita po standardu EN ISO 945. Prav tako sem, s pomočjo optične mikroskopije, opredelil delež ferita in perlita v sivi litini s kroglastim grafitom. Cilj naloge je bil opisati tudi rezultate opravljenega preizkusa, katerega sem opravil na termo-mehanskem stimulatorju GLEEBLE 1500D. Iz kemijske in mikrostrukturne analize sem potrdil, da je šlo za Si-Mo litino. Pri DSC analizi smo ugotovili referenčne temperature strjevanja in transformacije v trdnem, preiskovane SGI litine. Iz preizkusa termičnega utrujanja preiskovanega vzorca pa smo prikazali, da dolžina razpok narašča s povišanjem temperature segrevanja preiskovanega vzorca in s povečanjem števila ciklov.

• Language: Slovenian
• Keywords: železove zlitine, siva litina, siva litina s kroglastim grafitom, STA analiza, termično utrujanje materialov
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-119793
• COBISS.SI-ID: 31259139
• Publication date in RUL: 11.09.2020

Secondary language

• Language: English
• Title: Characterization of defects in spheroidal graphite cast iron casting

Abstract

In metallurgy, structure of studied object has a great impact on further research. This is the main reason why characteristics of grey iron was established. Grey iron is also one of the most common groups of materials. Characteristics of nodular cast iron is researched with different tests. For this purpose, I used diferential thermal analysis (DTA), which shows us the temperature range of transformation. The objective of this diploma is also to define microstructure of nodular cast iron. This test was made with optical microscopy, where the shape, size and distribution was analysed according to standard EN ISO 945. The proportion of ferrite and perlite in nodular cast iron was also defined by optical microscopy. The aim of this assignment was also to describe the results of the test, which was performed on the GLEEBLE 1500D Thermo-Mechanical Stimulator. The chemical and microstructural analysis, shows that it was a Si-Mo cast iron. With DSC analysis, reference areas of solidification and transformation into currently investigated SGI castings were identified. From the test of thermal fatigue of the investigated sample, we showed that the crack length increases with increasing heating temperature of the investigated sample and with increasing number of cycles.

• Keywords: iron alloys, grey iron, nodular cast iron, STA analysis, thermal fatigue of materials