Vpliv parametrov vročega preoblikovanja na rekristalizacijsko območje pri odkovkih iz aluminijeve zlitine EN AW 6082 : magistrsko delo

Stupan Rozman, Irena (author), Fajfar, Peter (mentor), Dovnik, Primož (comentor)

Pri različnih parametrih, ki imajo največji vpliv na debelino rekristalizacijskega območja, smo izvedli kovanje odkovkov iz zlitine EN AW 6082. Med procesom vročega preoblikovanja pride do kopičenja dislokacij, dinamične rekristalizacije in rasti zrn, kar vpliva na velikost zrn v mikrostrukturi in posledično na tok materiala. Rast zrn se pojavi med procesom vroče deformacije in nadaljuje tudi po zaključku predelave in rekristalizacije. Cilj naloge je bil raziskati kateri izmed parametrov, med procesom vročega preoblikovanja, najbolj vpliva na debelino rekristalizacijskega območja, na mehanske lastnosti in trdoto. Poskusi so se izvedli na več odkovkih, pri čemer so bili narezki segreti na različne temperature, pri različnih časih. Izpostavljeni so bili večkratnemu segrevanju. Ugotavljal se je morebiten vpliv hladnega ali toplega orodja pri kovanju. S simulacijo programa Deform smo določili območja kjer pride do največjih deformacij. Z meritvami debeline rekristalizacijskega območja je bilo ugotovljeno, da se optimalna temperatura v peči za segrevanje narezkov giblje med 520 °C in 550 °C. Optimalna temperatura orodja je 190 °C. Temperatura valjanca pred kovanjem se giblje med 460 °C in 507 °C. Narezki se lahko ponovno segrejejo na željeno temperaturo en krat. Homogena porazdelitev mikrostrukture in homogena porazdelitev drobnih izločkov sekundarne faze imata na trdoto največji vpliv. Najvišje vrednosti mehanskih lastnosti se dosežejo, ko se izločki iz koherentnih preoblikujejo v nekoherentne. Na območju brade in območju velikih deformacij je opaziti nagnjenost k rasti grobo zrnate strukture. To pripisujemo posledici večjega deleža uskladiščene energije, ki nastane med deformacijo. To se je potrdilo s simulacijo s programom Deform.

• Language: Slovenian
• Keywords: Zlitina EN AW 6082, toplotna obdelava, vplivni faktorji, rekristalizacijsko območje, trdota.
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [I. Stupan Rozman]
• Year: 2022
• Number of pages: XV, 55 f.
• PID: 20.500.12556/RUL-141659
• UDC: 669.187.25(043.2)
• COBISS.SI-ID: 130443011
• Publication date in RUL: 04.10.2022

STUPAN ROZMAN, Irena, 2022, Vpliv parametrov vročega preoblikovanja na rekristalizacijsko območje pri odkovkih iz aluminijeve zlitine EN AW 6082 : magistrsko delo [online]. Master’s thesis. Ljubljana : I. Stupan Rozman. [Accessed 30 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=141659

Secondary language

• Language: English
• Title: Influence of hot forming parameters on recrystallization zone for forgings from aluminium alloy EN AW 6082 : master's thesis

Abstract

With different parameters that have the greatest influence on the thickness of the recrystallization zone, we performed the forging from the EN AW 6082 alloy. During the hot forming process, the accumulation of dislocations, dynamic recrystallization and grain growth occur, which affects the size of the grains in the microstructure and, consequently, the material flow. Grain growth occurs during the hot deformation process and continues even after the completion of processing and recrystallization. The main aim of this thesis was to investigate which of the parameters, during the process of hot transformation, has the greatest influence on the thickness of the recrystallization zone, on the mechanical properties and hardness. Experiments were carried out on several forgings, where the cutting bullets were heated to different temperatures, at different times. They were exposed to repeated heating. The possible influence of cold or warm tools during forging was noted. With the simulation of the program Deform, we determined the areas where the greatest deformations occur. By measuring the thickness of the recrystallization zone, it was found that the optimal temperature in the furnace for heating the cutting bullets is between 520 °C and 550 °C. The optimal temperature of the tool is 190 °C. The temperature of the rolling stock before forging varies between 460 °C and 507 °C. The cutting bullets can be reheated to the desired temperature once. The homogeneous distribution of the microstructure and the homogeneous distribution of the fine secretions of the secondary phase have the greatest influence on the hardness. The highest values of mechanical properties are reached when the precipitates are transformed from coherent to incoherent. There is a tendency to grow a coarse-grained structure in the burr area and the area of large deformations. We attribute this to the consequence of a larger share of stored energy, which is generated during deformation. This was confirmed by simulation with the program Deform.

• Keywords: Alloy EN AW 6082, heat treatment, influencing factors, recrystallization zone, hardness.