Utjecaj sabijanja na tvrdoću čelika

master's thesis

• Title (english): Influence of compression on hardness steel
• Author: Klara Šimić
• Mentor: Martina Lovrenić-Jugović (mentor)
• Mentor: Željko Grubišić (pomoć pri izradi, neposredni voditelj)
• Committee member: Ljerka Slokar Benić (predsjednik povjerenstva)
• Committee member: Martina Lovrenić-Jugović (član povjerenstva)
• Committee member: Ivan Jandrlić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2022-12-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

Ovaj diplomski rad sastoji se od teorijskog i eksperimentalnog dijela. U teorijskom dijelu obrađeni su mehanizmi očvrsnuća metalnih materijala, s posebnim naglaskom na proces deformiranja hladnim sabijanjem. Dane su teorijske osnove provođenja statičkog vlačnog testa, mjerenja tvrdoće Vickersovom metodom te primjene metode konačnih elemenata za numeričku simulaciju sabijanja. U eksperimentalnom dijelu rada na čeliku za poboljšavanje 42CrMo4 (Č.4732) valjkastog oblika proveden je eksperiment sabijanja na hidrauličkoj preši s različitim iznosima opterećenja od: 8t, 14t, 20t i 24t. Nakon provedenog eksperimenta na sabijenim uzorcima provela se metalografska analiza te izmjerila tvrdoća Vickersovom metodom po uzdužnom presjeku sabijenih valjaka. Također je provedena nelinearna numerička simulacija sabijanja valjka s karakteristikama materijala dobivenim iz statičkog vlačnog testa. Izmjerene vrijednosti tvrdoće povećavaju se sa stupnjem sabijanja što ukazuje na pojavu očvrsnuća materijala. Provedena je i usporedba rezultata naprezanja dobivenih numeričkom simulacijom s rezultatima izmjerenih tvrdoća i metalografskih snimaka mikrostrukture, na kojima se jasno uočavaju zone deformacija prilikom sabijanja.

Abstract (english)

This master’s thesis consists of a theoretical and an experimental part. In the theoretical part, the mechanisms of strengthening metallic materials are discussed, with special emphasis on the process of deformation by cold compression. The theoretical basis of conducting a static tensile test, hardness measurement using the Vickers method, and the application of the finite element method for numerical simulation of compaction are given. In the experimental part of the paper on the hardening steel 42CrMo4 (Č.4732) cylindrical shape, a compression experiment was carried out on a hydraulic press with different load amounts: 8t, 14t, 20t, and 24t. After the experiment on the compressed samples, a metallographic analysis was carried out and the hardness was measured by the Vickers method on the longitudinal section of the compressed cylinders. A non-linear numerical simulation of the compressed cylinder with material characteristics obtained from a static tensile test was also performed. The measured hardness values increase with the degree of deformation, which indicates the occurrence of material strengthening. A comparison of the stress results obtained by numerical simulation with the results of measured hardnesses and metallographic images of the microstructure, where deformation zones during compression are clearly observed, was also carried out.

• Keywords: sabijanje; čelik za poboljšavanje; tvrdoća; metalografska analiza; numerička simulacija
• Keywords (english): compression; hardening steel; hardness; metallographic analysis; numerical simulation
• Language: croatian
• URN:NBN: urn:nbn:hr:115:193512
• Project: Number: KK.01.1.1.02.0022; Title: Virtulab – Integrirani laboratorij za primarne i sekundarne sirovine; Acronym: Virtulab; Leader: Sibila Borojević Šoštarić; Jurisdiction: Croatia; Funder: EK; Funding stream: EFRR
• Project: Number: RC.2.2.10-0005; Title: Centar za ljevarstvo - SIMET; Title: Center for Foundry Technology - SIMET; Acronym: SIMET; Leader: Zdenka Zovko Brodarac; Jurisdiction: Croatia; Funder: EK; Funding stream: EFRR
• 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: 2022-12-05 09:28:41