Modeliranje zamornog ponašanja densificiranog sinteriranog čelika

master's thesis

• Title (english): Modelling of fatigue behaviour of densified sintered steel
• Author: Pavao Banić
• Mentor: Tomislav Lesičar (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-03-29, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Tijekom prethodnih godina metalurgija praha postala je sve popularnija metoda proizvodnje materijala jer omogućuje niže troškove proizvodnje i visoku iskoristivost materijala u usporedbi s klasičnom metalurgijom. U metalurgiji praha često se koristi sinterirani čelik dobiven postupkom sinteriranja, gdje se praškasti materijal preko kalupa tlači u konačni oblik, te potom toplinski obrađuje. Pritom u jezgri materijala nastaju pore i gustoća je manja u usporedbi s čelikom dobivenim klasičnom metalurgijom. U svrhu postizanja boljih mehaničkih svojstava komponenata izrađenih od sinteriranog čelika podvrgnutih zamoru uslijed klizno-valjnog kontakta, provodi se densifikacija (progušćivanje) površinskog sloja. Kako bi se numeričkim simulacijama opisalo konstitutivno ponašanje komponenti od densificiranog sinteriranog čelika, potrebno je modelirati promjenjiva materijalna svojstva materijala u ovisnosti o gustoći.
U ovom diplomskom radu razmatrat će se sinterirani čelik Astaloy Mo+0,2C gustoće 6,5 g/cm3, kojem je površinski sloj progušćen do gustoće 7,5 g/cm3. U razmatranje su uzete dvije dubine densificiranog sloja: 0,5 mm i 1 mm. U radu je:
1. određena ovisnost parametara konstitutivnog ponašanja sinteriranog čelika o gustoći materijala temeljem rezultata eksperimentalnih ispitivanja provedenih za tri različite gustoće materijala.
2. numeričkim modeliranjem cikličkog testa određen utjecaj densifikacije na zamorno ponašanje densificiranog materijala.
Za provedbu numeričkih simulacija primijenjen je komercijalni programski paket ABAQUS.

Abstract (english)

In recent years, powder metallurgy technology has become increasingly popular, because it enables lower production costs and higher material utilization compared to classical metallurgy. One of the frequently used materials in powder metallurgy is sintered steel. It is obtained by the sintering process, where the powder material is pressed into the final shape via mold, followed by heat treatment. During the process, pores appear in the core of the material. That results in lower material density compared to steel obtained by classical metallurgy. The surface layer is usually densified to achieve better mechanical properties of components made of sintered steel subjected to fatigue due to sliding-rolling contact. In order to describe the constitutive behaviour of densified sintered steel components by numerical simulations, it is necessary to model the variable material properties depending on the density.
This thesis considers the sintered steel Astaloy Mo+0,2C with a density of 6,5 g/cm3, whose surface layer has been densified to a density of 7,5 g/cm3. Two depths of the densified layer were taken into consideration: 0,5 mm and 1 mm. In this paper:
1. Dependence of constitutive behaviour parameters of sintered steel on material density was determined based on the results of experimental tests carried out for three different material densities.
2. The influence of densification on the fatigue behaviour of the densified material was determined by numerical modelling of the cyclic test.
The commercial software package ABAQUS was used to perform the numerical simulations.

• Keywords: sinterirani čelik; densifikacija; densificirani materijal; numeričko modeliranje; metoda konačnih elemenata; metoda faznog polja; zamor; zamorno ponašanje
• Keywords (english): sintered steel; densification; densified material; numerical modelling; finite element method; phase field method; fatigue; fatigue behaviour.
• Language: croatian
• URN:NBN: urn:nbn:hr:235:435705
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-03-21 12:29:21