Karakteristike pojave Portevin-Le Chatelier efekta kod AlMg legura tijekom hladne deformacije

master's thesis

• Title (english): Characteristics of the appearance of the Portevin-Le Chatelier effect in AlMg alloys during cold deformation
• Author: Domagoj Kovačević
• Mentor: Ivan Jandrlić (mentor)
• Mentor: Lorena Mrkobrada (pomoć pri izradi, neposredni voditelj)
• Committee member: Ivana Ivanić (predsjednik povjerenstva)
• Committee member: Ivan Jandrlić (član povjerenstva)
• Committee member: Tin Brlić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2022-10-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

Aluminij i aluminijske legure su posljednjih godina postali nezamjenjiv materijal u mnogim industrijama. Neke legure aluminija pokazuju lokaliziranu deformaciju, takozvani Portevin-Le Chatelier efekt pri određenim brzinama deformacije i temperaturama. Takva lokalizirana deformacija uzrokuje razne probleme u industriji. Iz tog razloga je potrebno saznati više o Portevin-Le Chatelier efektu. U ovom radu istraživana je karakteristika pojave Portevin-Le Chatelier efekta kod AlMg legure tijekom hladne deformacije metodama statičkog vlačnog pokusa, termografije, digitalne korelacije slike (DIC) i metalografskom analizom mikrostrukture. Istraživanjem je utvrđena pojava Portevin-Le Chatelier efekta kod AlMg legure. Metodom digitalne korelacije slike je utvrđeno kako je pojava Portevin-Le Chatelier efekta brza i jasno uočljiva na DIC videu te kako dolazi do skokovitih promjena u deformaciji. Iz rezultata dobivenih metodom termografije je utvrđeno da tijekom skokovitog porasta u deformaciji dolazi do skokovitog porasta u temperaturi. Utvrđeno je da su skokovite promjene u deformaciji i temperaturi međusobno povezane. Ispitivanjem mikrostrukture je utvrđeno da je ispred PLC linije lijevana struktura, a na samoj liniji fronte dolazi do znatne deformacije i preorijentiranja zrna u smjeru razvlačenja.

Abstract (english)

In recent years, aluminum and aluminum alloys have become an irreplacable material in many industries. Some aluminum alloys exhibit localized deformation, the so-called Portevin-Le Chatelier effect, at certain deformation rates and temperatures. Such localized deformation causes various problems in industry. For this reason, it is necessary to learn more about Portevin-Le Chatelier effect. In this paper, the characteristics of the appearance of the PortevinLe Chatelier effect in AlMg alloys during cold deformation were investigated by static tensile test, thermography, digital image correlation and metallographic microstructure analysis. Research determined the occurence of the Portevin-Le Chatelier effect in the investigated AlMg
alloy. Using the digital image correlation, it was determined that the appearance of the PortevinLe Chatelier effect is fast and clearly visible phenomenon on the DIC video, and that during it sudden changes in deformation occur. During analysis using thermography method, it was determined that there are sudden increase in temperature. It was determined that sudden changes in deformation and in temperature are connected. Investigation of the microstructure revealed that in front of the PLC line there is a casting structure, at the front line itself there is considerable deformation and reorienation of the grains in the direction of stretching.

• Keywords: Portevin-Le Chatelier efekt; AlMg; ni pokuslegura; statički vlačni pokus; digitalna korelacija slike (DIC); termografija.
• Keywords (english): Portevin-Le Chatelier effect; AlMg alloy; static tensile test; digital image correlation (DIC); thermography.
• Language: croatian
• URN:NBN: urn:nbn:hr:115:984493
• 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: 2022-10-17 13:38:24