Utjecaj toplinske obrade na mehanička svojstva CuAlMn legure s prisjetljivosti oblika

master's thesis

• Title (english): The effect of heat treatment on mehanical properties of CuAlMn shape memory alloy
• Author: Irbas Škrinjarić
• 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: 2017-02-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy; Physical Metallurgy

Abstract

U ovom radu je prikazan utjecaj toplinske obrade na mikrostrukturu i mehanička svojstva
CuAlMn legure s prisjetljivosti oblika. Legura kemijskog sastava Cu – 8,30 % Al – 9,4 % Mn
(mas.%) je pripremljena iz čistih metala (>99,5 %), a zatim lijevana kontinuiranim
vertikalnim postupkom u zaštitnoj atmosferi argona. Najprije je proizveden ingot (Ø 110 x
180 mm) koji je korišten kao ulazni materijal za lijevanje šipke promjera Ø 8 mm. Provedena
su ispitivanja vlačne čvrstoće, granice razvlačenja, istezanja, kontrakcije i tvrdoće nakon
lijevanja, kaljenja (900 °C/30'/H2O) i popuštanja (100 – 300 °C/60'/H2O). Mikrostrukturna
karakterizacija uzoraka legure provedena je optičkom mikroskopijom (OM) i pretražnom
elektronskom mikroskopijom (SEM) s EDS analizom. S pretražnim elektronskim
mikroskopom je također provedena analiza prijelomnih površina. Nakon lijevanja CuAlMn
legure vlačna čvrstoća je iznosila 627 MPa, istezanje 8,5% i kontrakcij a 17,88 %. U lijevanoj
leguri utvrđena je djelomična prisutnost martenzitne faze dok je nakon kaljenja
mikrostruktura u potpunosti bila martenzitna. Značajan porast vlačne čvrstoće i značajan pad
istezanja uočeni su nakon popuštanja 200 °C/60'/H2O i 300 °C/60'/H2O.

Abstract (english)

This paper shows the effect of heat treatment on microstructure and mehanical properties of
CuAlMn shape memory alloy. Alloy with the chemical composition of Cu – 8.30 Al – 9.4 %
Mn (wt.%) was prepared from pure metals (>99.5 %) and then the alloy was casted by
continuously vertical casting tehnique, under protective argon atmosphere. The prepared ingot
(Ø 110 x 180 mm) was used as an input material for casting into 8 mm diameter bars. The
tensile strength, yield strength, elongation, reduction in area, and hardness were examined
after casting, quenching (900 °C/30'/H2O), and ageing (100 – 300 °C/60'/H2O). The samples
were microstructurally analysed using optical microscopy (OM) and scanning electron
microscopy (SEM) along with EDX analysis. Using scanning electron microscopy fracture
surfaces were also tested. Test resulted in tensile strength of 627 MPa, elongation of 8.5% and
reduction in area of 17.88% after casting of CuAlMn shape memory alloy. The alloys
revealed some martensitic phase after casting, but after quenching microstructure was
completely martensite. The tensile strength drastically increased and elongation drastically
decreased after ageing at 200 °C/60'/H2O and 300 °C/60'/H2O.

• Keywords: legure s prisjetljivosti oblika; CuAlMn; martenzit; toplinska obrada; mikrostruktura; mehanička svojstva
• Keywords (english): shape memory alloys; CuAlMn; martensite; heat treatment; microstructure; mehanical properties
• Language: croatian
• URN:NBN: urn:nbn:hr:115:107268
• 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
• Created on: 2017-02-28 08:18:52