Svojstva CuAlMnNi legure nakon kontinuiranog lijevanja i kaljenja

master's thesis

• Title (english): Properties of CuAlMnNi shape memory alloy after continuous casting and quenching
• Author: Alen Pinter
• Mentor: Mirko Gojić (mentor)
• Committee member: Stjepan Kožuh (predsjednik povjerenstva)
• Committee member: Mirko Gojić (član povjerenstva)
• Committee member: Tamara Holjevac Grgurić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2018-09-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

U ovom radu prikazan je utjecaj toplinske obrade na mikrostrukturu, tvrdoću i mehanizam prijeloma CuAlMnNi legure s prisjetljivosti oblika. Legura kemijskog sastava Cu –13 % Al – 2,5 %, Mn – 2,5 Ni (mas.%) je pripremljena iz čistih metala (>99,5 %), a potom je lijevana postupkom vertikalnog kontinuiranog lijevanja u zaštitnoj atmosferi argona. Dobiveni ingot dimenzija (Ø 110 x 180 mm) korišten je kao ulazni materijal za lijevanje šipke promjera Ø 8 mm. Nakon kontinuiranog lijevanja provedeno je kaljenje šipke na temperaturi 900 ºC u trajanju od 15 minuta. Šipka je potom ohlađena u vodi sobne temperature.
Mikrostruktura karakterizacija uzoraka CuAlMnNi legure provedena je optičkom mikroskopijom (OM) i pretražnom elektronskom mikroskopijom (SEM) opremljenom s energetsko disperzijskim spektrometrom (EDS). S pretražnim elektronskim mikroskopom je također provedena analiza prijelomnih površina. U uzorcima lijevanog stanja uočena je dvofazna mikrostruktura (α + β), dok je kod uzoraka nakon kaljenja u vodi s 900 °C uz dvofaznu mikrosturukturu zamijećena sporadična precipitacija martenzitne faze. Provedena su ispitivanja tvrdoće nakon lijevanja i kaljenja (900 °C/15 min/H2O). Tvrdoća kaljenog uzorka je bila veća od uzorka u lijevanom stanju. Fraktografskom analizom površine je ustanovljen transkristalni lom.

Abstract (english)

In this paper the influence of heat treatment on the microstructure, hardness and fracture mechanism of the CuAlMnNi shape memory alloy is shown. Alloy with the chemical composition of Cu -13% Al - 2.5%, Mn - 2.5 Ni (wt. %) was prepared from pure metal components (purity >99.5%) and then casted by vertical continuous casting process in the protective atmosphere of argon. The obtained ingot with dimension (Ø 110 x 180 mm) was used as the input material for the Ø 8 mm rod. After continous casting procedure, the rod was quenched at 900 ºC for 15 minutes. The rod was cooled at room temperature water.
The microstructural characterization of CuAlMnNi alloy was performed by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersion spectrometer (EDS). By scanning electron microscop an analysis of the fracture surfaces was carried out. The two-phase microstructure (α + β) was observed in the as-cast state, while in the case of quenched sample, a sporadic precipitation of the martensite phase was observed. Hardness tests measurement in as-cast state and after quenching (900 ° C/15 min/H2O) were performed. The hardness of the quenched sample was higher than the sample in the as-cast state. Fractographic surface analysis revealed transcrystalline type of fracture.

• Keywords: legure s prisjetljivosti oblika; CuAlMnNi; martenzit; toplinska obrada; mikrostruktura; mehanička svojstva
• Keywords (english): shape memory alloys; CuAlMnNi; martensite; heat treatment; microstructure; mechanical properties
• Language: croatian
• URN:NBN: urn:nbn:hr:115:472044
• 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: 2018-09-28 07:16:15