Dr. Alan Vaško

Committee: International Scientific Committee of Industrial and Manufacturing Engineering
University: University of Žilina, Facutly of Mechanical Engineering
Department: Department of Materials Engineering
Research Fields: nodular cast iron, silicon carbide, microstructure, mechanical properties,

Publications

2 Influence of Raw Material Composition on Microstructure and Mechanical Properties of Nodular Cast Iron

Authors: Juraj Belan, Lenka Hurtalova, Alan Vaško, Eva Tillová

Abstract:

The aim of this study is to evaluate the influence of raw material composition on the microstructure, mechanical and fatigue properties and micromechanisms of failure of nodular cast iron. In order to evaluate the influence of charge composition, the structural analysis, mechanical and fatigue tests and microfractographic analysis were carried out on specimens of ten melts with different charge compositions. The basic charge of individual melts was formed by different ratio of pig iron and steel scrap and by different additive for regulation of chemical composition (silicon carbide or ferrosilicon). The results show differences in mechanical and fatigue properties, which are connected with the microstructure. SiC additive positively influences microstructure. Consequently, mechanical and fatigue properties of nodular cast iron are improved, especially in the melts with higher ratio of steel scrap in the charge.

Keywords: Microstructure, Silicon Carbide, Mechanical Properties, nodular cast iron

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1 The High Temperature Damage of DV – 2 Turbine Blade Made from Ni – Base Superalloy

Authors: Juraj Belan, Lenka Hurtalova, Alan Vaško, Eva Tillová, Milan Uhríčik

Abstract:

High pressure turbine (HPT) blades of DV – 2 jet engines are made from Ni – based superalloy. This alloy was originally manufactured in the Soviet Union and referred as ŽS6K. For improving alloy’s high temperature resistance are blades coated with Al – Si diffusion layer. A regular operation temperature of HPT blades vary from 705°C to 750°C depending on jet engine regime. An overcrossing working temperature range causes degradation of the protective coating as well as base material which microstructure is formed by the gamma matrix and strengthening phase gamma prime (forming small particles in the microstructure). Diffusion processes inside the material during exposition of the material to high temperatures causes mainly coarsening of the gamma prime particles, thus decreasing its strengthening effect. Degradation of the Al – Si coating caused its thickness growth. All the microstructure changes and coating layer thickness growth results in decreasing of the turbine blade operation lifetime.

Keywords: gamma prime phase, turbine blade, Alitize coating layer, high temperature degradation, Ni – base superalloy ŽS6K

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Abstracts

3 Change of Internal Friction on Magnesium Alloy with 5.48% Al Dependence on the Temperature

Authors: Alan Vaško, Milan Uhríčik, Andrea Soviarová, Zuzana Dresslerová, Peter Palček

Abstract:

The article is focused on the analysis changes dependence on the temperature on the magnesium alloy with 5,48% Al, 0,813% Zn and 0,398% Mn by internal friction. Internal friction is a property of the material is measured on the ultrasonic resonant aparature at a frequency about f = 20470 Hz. The measured temperature range was from 30 °C up to 420 °C. Precisely measurement of the internal friction can be monitored ongoing structural changes and various mechanisms that prevent these changes.

Keywords: temperature, Resonant Frequency, Magnesium Alloy, internal friction

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2 Influence of Raw Material Composition on Microstructure and Mechanical Properties of Nodular Cast Iron

Authors: Juraj Belan, Lenka Hurtalova, Alan Vaško, Eva Tillová

Abstract:

The aim of this study is to evaluate the influence of raw material composition on the microstructure, mechanical and fatigue properties and micromechanisms of failure of nodular cast iron. In order to evaluate the influence of charge composition, the structural analysis, mechanical and fatigue tests and micro fractographic analysis were carried out on specimens of ten melts with different charge compositions. The basic charge of individual melts was formed by a different ratio of pig iron and steel scrap and by different additive for regulation of chemical composition (silicon carbide or ferrosilicon). The results show differences in mechanical and fatigue properties, which are connected with the microstructure. SiC additive positively influences microstructure. Consequently, mechanical and fatigue properties of nodular cast iron are improved, especially in the melts with the higher ratio of steel scrap in the charge.

Keywords: Microstructure, Silicon Carbide, Mechanical Properties, nodular cast iron

Procedia PDF Downloads 451
1 The High Temperature Damage of DV–2 Turbine Blade Made from Ni–Base Superalloy

Authors: Juraj Belan, Lenka Hurtalova, Alan Vaško, Eva Tillová, Milan Uhríčik

Abstract:

High-pressure turbine (HPT) blades of DV–2 jet engines are made from Ni–base superalloy, a former Soviet Union production, specified as ŽS6K. For improving its high-temperature resistance are blades covered with Al–Si diffusion layer. A regular operation temperature of HPT blades vary from 705°C to 750°C depending on jet engine regime. An over-crossing working temperature range causes degradation of protective alitize layer as well as base material–gamma matrix and gamma prime particles what decreases turbine blade lifetime. High-temperature degradation has mainly diffusion mechanism and causes coarsening of strengthening phase gamma prime and protective alitize layer thickness growing. All changes have a significant influence on high-temperature properties of base material.

Keywords: alitize layer, gamma prime phase, high-temperature degradation, Ni–base superalloy ŽS6K, turbine blade

Procedia PDF Downloads 382