diplomsko delo
Tomaž Ivančič (Author), Goran Kugler (Mentor)

Abstract

Rekristalizacija med vročo deformacijo ima velik vpliv na končne lastnosti materiala. Zato je bilo v tej smeri razvitih že veliko različnih pristopov k modeliranju tega pomembnega pojava. V diplomskem delu smo uporabili nov pristop k modeliranju dinamične rekristalizacije, ki temelj na teoriji povprečnega polja. Za opis razvoja gostote dislokacij med deformacijo smo uporabili KM-model, rast zrn smo opisali na osnovi določitve energije sistema in uporabe Lagrangeevega formalizma. Za določitev začetka nukleacije smo uporabili pristop, ki sta ga predlagala Roberts in Ahlblom. Raziskovali smo vplive posameznih mehanizmov na potek dinamične rekristalizacije, na katere smo vplivali z s parametri modela. Pomagali smo si tudi z eksperimentalnimi krivuljami tečenja in z mikrostrukturami pred in po plastični deformaciji v vročem za jeklo S690QL. Poiskali smo takšne parametre modela, da so se rezultati simulacije čim bolje ujeli z eksperimentalnimi rezultati. Ugotovili smo, da se model dobro odziva na spremembe temperature in hitrosti deformacije in je zmožen opisati vse fenomene in odvisnosti, ki so opaženi pri eksperimentalnih rezultatih.

Keywords

preoblikovanje v vročem;dinamična rekristalizacije;dinamična poprava;deformacijsko utrjevanje;Lagrangeev formalizem;teorija povprečnega polja;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [T. Ivančič]
UDC: 669
COBISS: 86621443 Link will open in a new window
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Other data

Secondary language: English
Secondary title: parametric analysis of the mean field theory model of dynamic recrystallization
Secondary abstract: Recrystallization during hot working has large influence on the final properties of the material. Therefore, many different approaches have already been developed in this direction to model this important phenomenon. In the diploma work we have used a new approach to model dynamic recrystallization based on mean field theory. A KM model was used to describe the evolution of dislocation density during deformation, grain growth was described by determining the energy of the system and using the Lagrangian formalism. To determine the onset of nucleation, we used the approach proposed by Roberts and Ahlblom. We investigated the influences of individual mechanisms on the kinetics of dynamic recrystallization, which were affected by the parameters of the model. The experimental flow curves and microstructures before and after hot plastic deformation for S690QL steel were used to determine the material parameters. We determined the model parameters to obtain the best agreement between the simulation and experimental results. It was found that the model responds well to variations in temperature and strain rate, and that it can describe all the phenomena and dependencies observed in the experimental results.
Secondary keywords: hot working;dynamic recrystallization;dynamic recovery;strain hardening;Lagrangian formalism;mean field theory;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za materiale in metalurgijo
Pages: IX, 25 f.
ID: 13525424