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Deformation of tool steels after quenching in vacuum furnaces
Abu Khait, Yosef ; Němec, Karel (referee) ; Pacal, Bohumil (advisor)
In this thesis, the deformation stages, which take place in tool steels after quenching in vacuum furnaces, were studied. This study was focused on the heating and cooling conditions during this type of quenching. In the experimental part, the deformation changes in particular samples made of tool steel after vacuum quenching were analyzed. Minor changes in the volume of samples at higher quenching temperatures compared to lower temperatures were observed.
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The Influence of Structure and Heat Treatment on Properties of Steels for Bearings
Pytlíčková, Kateřina ; Dočkal, Ing, Michael (referee) ; Věchet, Stanislav (advisor)
Heat treatment influences structure and characteristics of treatmented material. Good heat treatment of steels for bearings ensures hardness of matrix 60 - 65 HRC, whereas structure has be formed by tempered fine needle-shaped martensite with definite part of residual austenite. Carbides should be evenly dispersed, they mustn´t create carbide network and carbide lines. Quality of steels for bearings is also influenced by volume and morphology of inclusions in the matrix. In this diploma thesis various conditions of heat treatment were to be set up with the aim of choose the optimal ones. These ensures perfect martensite transformation and full hardening of all component. Quenching from 760 °C – 770 °C was quite unsatisfactory. At this temperature resulting structure was ferritic-perlitic, because martensite transformation did not pass. Too long hold on hardening temperature also had unfavourable influence on resulting structure and characteristics. In this case, structure was created by very coarse needle-shaped martensite. Coarsening of martensite needle locally exceeded maximum allowed level. In the structure there was also possible to watch partly soluted globular carbides. Optimal heat treatment is quenching from 850 °C – 870 °C followed by tempering at 220 °C. Resulting structure quite agree with above-mentioned needs. This heat treatment can be recommended for technical practise.
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Heat processing principle of operation thermal resistance annealing.
Špičková, Petra ; Humár, Anton (referee) ; Kalivoda, Milan (advisor)
The project assigned for the bachelors study program B 2307 analyses the theory of heat processing in general and furthermore resistance annealing with the focus on the technology developed by the company Heatmasters. Examples of processing methods used at other technology providers are presented, inclu-ding documentation and datasheets. Resistance annealing is based on the heat transfer from a resistive wire, which heats up by electrical current. The thermal energy is then transferred to the target material through heat radiation or con-ductance. The resistance heat processing is used both for welding and for an-nealing. Nowadays is the documentation and recording of the heat processing of significant importance. Possibilities exist that allow recording of temperature during the entire cycle of the heat processing and subsequently providing the result evidence in a form of a certificate.
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Design of material for drawing tools
Petrecký, Adam ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
Bachelor thesis deals with optimalization of material choice and its heat treatment for cold work forming tools. The thesis deals with specific failure of seizure during the cold forming of high strenght steel for automotive. First part deals with theory of cold forming and tool steels made for this purpose. The main goal of the thesis was to discover cause of the failure and deduce solution as choice of alternative material with its proper heat treatment and surface coating. Solution has to show higher lifespan and also has to deliver economical benefit.
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Magnetocrystalline anisotropy of Ni-Mn-Ga-Co-Cu martensite
Rameš, Michal ; Straka, Ladislav ; Sozinov, A. ; Heczko, Oleg
The martensites of Heusler alloys based on Ni-Mn-Ga exhibit magnetically-induced reorientation resulting in giant field-induced strain. Up to 12% strain was observed in Ni-Mn-Ga-Co-Cu with 4 at.% of Co and Cu. The driving force of the phenomenon is the magnetocrystalline anisotropy. We studied evolution of the anisotropy with temperature and compositions using magnetiyation curve measurements in four different single crystalline Ni-Mn-Ga-Co-Cu and compared with non-doped Ni-Mn-Ga. The anisotropy of martensite decreases with increasing average doping (Co+Cu)/2 but it does not scale with tetragonal ratio or valence electron concentration.
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Influence of surface morphology on fatigue behavior of metastable austenitic stainless steel AISI 347 at ambient temperature and 300°C
Smaga, M. ; Skorupski, R. ; Mayer, P. ; Kirsch, B. ; Aurich, J. C. ; Raid, I. ; Seewig, J. ; Man, Jiří ; Eifler, D. ; Beck, T.
The effect of surface modification by cryogenic turning on fatigue behavior of metastable austenitic stainless steel AISI 347 was investigated in stress-controlled fatigue tests at ambient temperature (AT) and 300 °C in air. Five different surface morphologies were manufactured by the variation of turning parameters. Surface and near surface morphology were comprehensively characterized by various experimental techniques. The experimental data on the cyclic deformation behavior, stress-strain response and fatigue life for all surface morphologies are reported.
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Deformation of tool steels after quenching in vacuum furnaces
Abu Khait, Yosef ; Němec, Karel (referee) ; Pacal, Bohumil (advisor)
In this thesis, the deformation stages, which take place in tool steels after quenching in vacuum furnaces, were studied. This study was focused on the heating and cooling conditions during this type of quenching. In the experimental part, the deformation changes in particular samples made of tool steel after vacuum quenching were analyzed. Minor changes in the volume of samples at higher quenching temperatures compared to lower temperatures were observed.
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The Influence of Structure and Heat Treatment on Properties of Steels for Bearings
Pytlíčková, Kateřina ; Dočkal, Ing, Michael (referee) ; Věchet, Stanislav (advisor)
Heat treatment influences structure and characteristics of treatmented material. Good heat treatment of steels for bearings ensures hardness of matrix 60 - 65 HRC, whereas structure has be formed by tempered fine needle-shaped martensite with definite part of residual austenite. Carbides should be evenly dispersed, they mustn´t create carbide network and carbide lines. Quality of steels for bearings is also influenced by volume and morphology of inclusions in the matrix. In this diploma thesis various conditions of heat treatment were to be set up with the aim of choose the optimal ones. These ensures perfect martensite transformation and full hardening of all component. Quenching from 760 °C – 770 °C was quite unsatisfactory. At this temperature resulting structure was ferritic-perlitic, because martensite transformation did not pass. Too long hold on hardening temperature also had unfavourable influence on resulting structure and characteristics. In this case, structure was created by very coarse needle-shaped martensite. Coarsening of martensite needle locally exceeded maximum allowed level. In the structure there was also possible to watch partly soluted globular carbides. Optimal heat treatment is quenching from 850 °C – 870 °C followed by tempering at 220 °C. Resulting structure quite agree with above-mentioned needs. This heat treatment can be recommended for technical practise.
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