Utjecaj žarenja na svojstva kontinuirano lijevane Cu - Al legure

master's thesis

• Title (english): The effect of annealing on properties of continuously casted Cu - Al alloy
• Author: Vlado Džomba
• Mentor: Stjepan Kožuh (mentor)
• Committee member: Mirko Gojić (predsjednik povjerenstva)
• Committee member: Stjepan Kožuh (član povjerenstva)
• Committee member: Tamara Holjevac Grgurić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2018-02-28, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

U ovom radu je prikazan utjecaj toplinske obrade (ţarenja na 900 °C u trajanju 15 i 30 minuta)
na mikrostrukturu, mikrotvrdoću i mehanička svojstva Cu - 9,1Al legure. Navedena legura
predstavlja predleguru za dobivanje Cu - Al - Mn - Zn legure s efektom prisjetljivosti oblika.
Najprije je proizveden ingot dimenzija Ø 110 x 180 mm koji je pretaljen te kontinuirano
lijevan u oblik cilindrične šipke promjera 8 mm. EDS analiza kemijskog sastava je potvrdila
da je lijevanje Cu - 9,1Al legure uspješno provedeno (proizvedena je legura homogenog
sastava). Optičkom i pretraţnom elektronskom mikroskopijom primijećena je prisutnost
dvofazne α + β mikrostrukture koja se zadrţava i nakon toplinske obrade iako dolazi do
odreĎene mjestimične promjene morfologije α - faze. DSC analizom je primijećena jedna
endotermna promjena toplinskog toka prilikom zagrijavanja koja vjerojatno predstavlja α→β
transformaciju i jedna egzotermna promjena toplinskog toka prilikom hlaĎenja koja vjerojatno
predstavlja β→α transformaciju. Uočene razlike mikrotvrdoće i vlačne čvrstoće su neznatne
dok istezanje opada prilikom duţeg izlaganja ţarenju. Promjene u iznosu kontrakcije
podudaraju se s promjenom vrijednosti granice razvlačenja.

Abstract (english)

In this work it is shown the effect of heat treatment (annealing at 900 °C in duration 15 and 30
minutes) on microstructure, microhardness and mehanical properties of Cu - 9,1Al alloy. This
alloy represents prealloy for production of Cu - Al - Mn - Zn alloy with the shape memory
effect. At first it was produced ingot with dimensions Ø 110 x 180 mm which is remelted and
continously casted in the shape of cylindrical rod with diameter 8 mm. EDS analysis of
chemical composition has affirmed that cast of Cu - 9,1Al alloy is successfully done (alloy
with homogeneous composition is produced). With optical and scanning electron microscopy
was observed existence of dual-phase α + β microstructure which preserves after heat
treatment as well although certain sporadic shape changes of α - phase occurs. On DSC
analysis was noticed one endothermic change of the heat flow during the heating which
probably represents β→α transformation and one exothermic change of the heat flow during
the cooling which probably represents β→α transformation. Differences observed in the
microhardness and tensile strength values are insginificant while the strain decreases with
longer duration of the annealing. Changes in the amount of contraction coincides with
changes in the value of the yield strenght.

• Keywords: Cu - Al legura; žarenje; mikrostruktura; mehanička svojstva; DSC analiza
• Keywords (english): Cu - Al alloy; annealing; microstructure; mehanical properties; DSC analysis
• Language: croatian
• URN:NBN: urn:nbn:hr:115:868483
• Project: Number: IP-2014-09-3405; Title: Dizajniranje mikrostrukture i funkcionalnih svojstava legura s prisjetljivosti oblika na bazi bakra; Acronym: DMFP-CuSMA; Leader: Mirko Gojić; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Graduate study program Metallurgy; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka metalurgije (magistar/magistra inženjer/inženjerka metalurgije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Public note: Ovaj je rad financirala Hrvatska zaklada za znanost projektom IP-2014-09-3405.
• Created on: 2018-03-02 09:59:14