Utjecaj deformacije i toplinske obrade na strukturu hladno vučene bakrene žice

master's thesis

• Title (english): Influence of deformation and heat treatment on structure of the cold drawn copper wire
• Author: Vedran Torman
• Mentor: Ivan Jandrlić (mentor)
• Mentor: Franjo Kozina (pomoć pri izradi, neposredni voditelj)
• Committee member: Stjepan Kožuh (predsjednik povjerenstva)
• Committee member: Ivan Jandrlić (član povjerenstva)
• Committee member: Natalija Dolić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2021-10-28, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

Bakar je jedan od najvažnijih obojenih metala, zahvaljujući svojim dobrim svojstvima, još je uvijek nezamjenjiv u primjeni proizvodnje vodiča i u drugimprimjenama.Bakar u lijevanom stanju nije primjenjiv za proizvodnju vodiča iz nekoliko razloga, stoga se naknadno provode postupci deformacije i rekristalizacije kako bi mu se poboljšala svojstva. Istraživanja u ovom diplomskom radu su provedena na žici proizvedenoj UPCAST postupkom vertikalnog lijevanja i naknadno hladno provlačenoj kroz matrice. Lijevana žica promjera 8 mm jenaknadno postupkom kontinuiranog provlačenja kroz više matrica reducirana do konačnog promjera od 2.6 mm. Pri postupku proizvodnje i prerade bakrene žice, u njoj dolazi do različitih promjena u strukturi, mehaničkim svojstvima i električnim svojstvima. U cilju promatranja ovih promjena provedena su strukturna ispitivanja, ispitivanje tvrdoće i mjerene su vodljivosti žice u pojedinim fazama proizvodnje. Ispitivanja su vršena pri stupnjevima redukcije od 24, 46 i 67.5%. Rezultati ispitivanja opisuju strukturne promjenekoje se dešavaju nakon provođenja pojedine redukcija, te isto takoutjecaj redukcije na tvrdoću i vodljivosti žice, kao i utjecaj toplinskog postupka žarenja na strukturu i vodljivost bakrene žice. Rezultati ukazuju kako početna lijevana grubozrnata struktura tijekom redukcije prelazi u sitnozrnatu strukturu usmjerenu u smjeru odvijanja plastične deformacije. Uslijed toga dolazi do smanjenja vodljivosti, što se naknadnom toplinskom obradom mijenja te se ostvaruje dobra vodljivost uz zadržavanje dobrih mehaničkih svojstava žice. Strukturna istraživanja također ukazuju kako nakon toplinske obrade u strukturi bakrenog vodiča dolazi do formiranja kristala blizanaca.

Abstract (english)

Copper is one of the most important non-ferrous metals, thanks to its good properties it is still irreplaceable in the application for conductors of electricity, and in other uses. Copper in its as cast state is not applicable in the production of conductors for several reasons. Deformation and recrystallization processes are subsequently performed to improve its properties. The research in this graduate thesis was conducted on a copper wire produced by the UPCAST vertical casting process and subsequently cold drawn. The as cast wire with a diameter of 8 mm was subsequently reduced to the final dimension by a continuous drawing process through several dies up to the wire thickness of 2.6 mm. During the production and processing of copper wire, various changes in structure, mechanical properties and electrical properties occur. In order to observe these changes, structural and hardness tests were performed and wire conductivities were measured at individual stages of production. The tests were performed on the wire at reductions of 24, 46 and 67.5%. The test results describe the structural changes that occur after the implementation of individual reductions, as well as the influence of reduction on the hardness and electrical conductivity of the wire, as well as the impact of the thermal annealing process on the structure and conductivity of copper wire. The results indicate that the initial coarse-grained structure in cast state, during reduction brakes down into a fine-grained structure orientated in the direction of plastic deformation. As a result, the conductivity is reduced, which is changed by subsequent heat treatment. After heat treatment a good conductivity is achieved while maintaining the better mechanical properties of the wire. Structural studies also indicate that after heat treatment, twin crystals form in the structure of the copper conductor.

• Keywords: bakrena žica; hladno provlačenje; struktura; tvrdoća; električna vodljivost
• Keywords (english): copper wire; cold drawing; structure; hardness; electrical conductivity
• Language: croatian
• URN:NBN: urn:nbn:hr:115:058296
• 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: 2021-11-09 09:56:55