diplomsko delo
Karina Šuntner (Author), Boštjan Markoli (Mentor)

Abstract

Aluminij kot čista kovina ima nizko trdnost in slabe mehanske lastnosti. Čisti aluminij je treba legirati za uporabo v visoko obremenjenih konstrukcijskih aplikacijah. Aluminijeve zlitine skupine 6XXX imajo odlične lastnosti, kot sta razmerje med nizko maso in visoko trdnostjo in sposobnost preoblikovanja zaradi dobre plastičnosti. Glavna legirna elementa sta Mg in Si, ki tvorita spojino Mg2Si. Ena izmed takšnih zlitin je zlitina EN AW 6082, ki se uporablja v avtomobilski industriji z namenom, da bi zaradi zmanjšanja mase odkovkov dosegli zahteve po manjši porabi goriva in izpušnih plinov. Poleg majhne teže aluminijski odkovki zagotavljajo izjemno trdnost, dobro odpornost proti koroziji in odpornost na utrujanje. Cilj diplomskega dela je bil metalografsko pripraviti vzorce aluminijeve zlitine EN AW 6082 za svetlobni mikroskop in primerjati mikrostrukturo med aluminijevim odkovkom s toplotno obdelavo T6 in aluminijevim odkovkom, ki je po kovanju ohlajen na zraku. Določevali smo velikosti zrn, merili trdoto vzorcev in izmerili električno upornost vzorcev s Foerster, sigmatestom 2.069. Po kovanju vzorcev smo drugi vzorec še toplotno obdelali po postopku T6. Pripravili mikrostrukturo za opazovanje faz in za opazovanje kristalnih zrn. Kristalna zrna v mikrostrukturi odkovka s toplotno obdelavo so po obrobni coni močno zrasla. Material je na površinskem sloju močno podvržen obsežni strižni deformaciji v primerjavi s sredino in s ponovnim dvigom temperature pride do rekristalizacije in zrna zrastejo. Z merjenjem trdote smo ugotovili, da je toplotna obdelava ključna za doseganje visoke trdote in da rekristalizirana zrna ne poslabšajo trdnosti oziroma mehanskih lastnosti.

Keywords

zlitina EN AW 6082;toplotna obdelava;mikrostrutkura;trdota;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [K. Šuntner]
UDC: 669
COBISS: 84852995 Link will open in a new window
Views: 209
Downloads: 29
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Other data

Secondary language: English
Secondary title: detection of macro and microstructure of aluminium forgings
Secondary abstract: Aluminum as a pure metal has low strength and poor mechanical properties. For use in high- strength structural applications, pure aluminum must be alloyed. Aluminum alloys of the 6XXX group have outstanding qualities, such as strength and formability. The main alloying elements are Mg and Si, which form the compound Mg2Si. One such alloy is the EN AW 6082 alloy, which is used in the automotive industry, where weight savings is a critical requirement for reduced fuel consumption and exhaust emissions. In addition to being lightweight, aluminium forgings provide superior structural rigidity, high strength, good corrosion resistance and fatigue resistance. The main objective of the thesis was to metallographically prepare samples of aluminum alloy EN AW 6082 for a light microscope and to compare the microstructure between aluminum forging with heat treatment T6 and aluminum forging, which is air-cooled after forging. Grain sizes were determined, the hardness of the samples was measured, and the electrical resistance of the samples was measured with a Foerster, sigmatest 2.069. After forging the samples, the second sample was heat treated in accordance with the T6 procedure.The microstructure was prepared for phase observation and crystal grain observation. Crystal grains in the microstructure forged by the heat treatment have grown strongly along the peripheral zone. The material is strongly subjected to extensive shear deformation on the surface layer, compared to the middle, and when the temperature rises again, recrystallization occurs and the grains grow. By measuring hardness, we found that heat treatment is key to achieving high hardness and that recrystallised grains do not impair strength or mechanical properties.
Secondary keywords: alloy EN AW 6082;heat treatment;microstructure;hardness;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za materiale in metalurgijo
Pages: XII, 50 f.
ID: 13356494