Utjecaj usitnjavanja zrna na mehanička svojstva aluminijskog odljevka

Bečirović, Tomislav (2013) Utjecaj usitnjavanja zrna na mehanička svojstva aluminijskog odljevka. = Master's thesis (Bologna) , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Bauer, Branko.

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Abstract (Croatian)

U okviru ovog rada ispitivan je utjecaj usitnjavanja zrna na mehanička svojstva aluminijskog odljevka. Ovaj rad sastoji se od dva dijela: teorijskog i eksperimentalnog. U teorijskom dijelu ukratko su objašnjena svojstva i primjena aluminijevih legura. Također je prikazan kratki pregled osnovnih teorija skrućivanja metala i legura, mehanizama nukleacije, odnosno započinjanja procesa skrućivanja te mehanizama rasta kristala. Objašnjen je postupak obrade taljevine usitnjavanjem zrna aluminijskih legura, potanko su objašnjene predlegure za usitnjavanje zrna te karakteristike i svojstva njima obrađene taljevine. U eksperimentalnom dijelu ispitivan je utjecaj obrade AlSi12 legure na mikrostrukturu i mehanička svojstva. U tu svrhu provedeno je lijevanje osnovne taljevine AlSi12 legure i osnovne taljevine s dodatkom AlTi10 predlegure. Lijevano je više odljevaka različitih dimenzija kako bi se mogao razmatrati utjecaj brzine hlađenja te kako bi se rezultati ispitivanja mogli višestruko uspoređivati. Pripremljeni su uzorci te je određen kemijski sastav zadane AlSi12 legure. Zatim su provedena radiografska, metalografska i mehanička ispitivanja. \Na temelju dobivenih rezultata pokazalo se da usitnjavanje zrna predlegurom AlTi10 povoljno utječe na mikrostrukturu legure, dolazi do poboljšanja mehaničkih svojstava, istezljivost se tek neznatno smanjila.

Abstract

In this paper it was tested how grain refinement influences mechanical properties of aluminium casting. This paper is composed of two parts: theoretical and experimental. In the theoretical part properties and application of aluminuim alloy were briefly discussed. There is also a concise overview of basic theories of solidification of metals and alloys, theories of nucleation mechanisims, that is initiating processes of solidifaction and mechanisms of crystal growing. The process of melt treatment by aluminum alloy grain refinement was explained; prealloys for grain refinement, characteristics and properties of the melt treated by those prealloys were described in great detail. In the experimental part it was tested how AlSi12 alloy treatment influences microstructure and mechanical properties. For that purpose the basic melt of AlSi12 alloy and the melt with the addition of AlTi10 prealloy were casted. More casts of various dimensions were casted in order to observe the influence of cooling speed and to repeatedly compare the testing results. The samples were prepared and the chemical composition of AlSi12 alloy was determined. After that radiographic, metallographic and mechanical testing were performed. On the basis of the gained results it was showed that grain refinement by AlTi10 prealloy has a positive influence on the alloy microstructure, mechanical properties are improved and ductility is decreased insignificantly.

Item Type: Thesis (Master's thesis (Bologna))
Uncontrolled Keywords: AlSi12 legura; skrućivanje; obrada taljevine; usitnjavanje zrna; mikrostruktura; mehanička svojstva
Keywords (Croatian): AlSi12 alloy, solidification, melt treatment, grain refinement, microstructure, mechanical properties
Divisions: 1200 Department of Technology > 1210 Foundry Chair
Date Deposited: 22 Sep 2014 18:00
Last Modified: 16 Oct 2015 12:50
URI: http://repozitorij.fsb.hr/id/eprint/2567

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