Rzeszów, Poland
Rzeszów, Poland

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Stopyra M.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow | Kielbus A.,Silesian University of Technology
Solid State Phenomena | Year: 2014

The casting defects, microstructure and hardness of of sand-cast Elektron 21 magnesium alloy was investigated. Visual and radiographic examination showed the presence of non-metallic inclusions and porosity. Quantitative analysis of microstructure was performed, no correlation between section thickness, grain size, volume fraction of eutectic areas and hardness was observed. Casting defects have influenced the cracking at magnesium casting/steel tube interface. © (2014) Trans Tech Publications, Switzerland.


Dybowski B.,Silesian University of Technology | Kielbus A.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow | Pasko J.,ZM WSK Rzeszow
Solid State Phenomena | Year: 2014

Magnesium alloys are one of the lightest structural metallic materials. Their specific strength and stiffness is comparable to this, characterizing aluminum alloys and even some groups of steel and titanium alloys. Their main disadvantage is low maximum working temperature (about 120°C for Mg-Al-Zn alloys). This led to development of Mg-RE-Zr alloys, which can work up to 250°C. The paper presents results of the investigations of influence of subsequent melting operations on the Elektron 21 and WE43 magnesium alloys. Elektron 21 alloy had been prepared from the pure ingots, while WE43 alloy from the scrap material. Mean plane section area of grains and eutectics volume fraction had been evaluated quantitatively. The results of the evaluation have been verified by means of Mann-Whitney U-Test and Kolmogorov-Smirnov statistical tests. The liquid metal treatment led to refinement of the grain only in Elektron 21 alloy (from Ā=3559μm2 to Ā=1849 μm2). Multiple modification of the WE43 alloy does not lead to further decrease of the mean plane section area of grains (from Ā=1638μm2 to Ā=1871 μm2). © (2014) Trans Tech Publications, Switzerland.


Poloczek L.,Silesian University of Technology | Dybowski B.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow' | Kielbus A.,Silesian University of Technology
Solid State Phenomena | Year: 2015

Majority structural elements from magnesium alloys are produced by means of casting. The big and complicated elements from magnesium alloys with RE addition are mainly sand cast. The aim of the research was to investigate the influence of wall thickness on the castability and microstructure of modern magnesium alloy with RE and Ag additions – QE22. Eight 145x98mm plates have been cast for the research. Their designed thickness was equal: 0.5mm, 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm as well as 6mm. The parameters of microstructure constituents in each cast has been estimated quantitatively. The critical wall thickness, at which liquid alloy fill the mould cavity completely, is equal 4mm. With decreasing wall thickness, percentage of filled cavity is decreasing linearly. Mean area of grain flat section increased 7 times in the thickest plate (from 501μm2 to 3773μm2). The volume fraction of eutectics as well as alloy hardness decreased in the thickest plate. © (2015) Trans Tech Publications, Switzerland.


Stopyra M.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow | Kielbus A.,Silesian University of Technology
Solid State Phenomena | Year: 2012

The paper presents analysis of section thickness' influence on microstructure of Elektron 21 and QE22 magnesium alloys in the form of a stepped casting test. Solid solution grain size and volume fraction of eutectic areas were measured using light microscope and stereological methods. The results showed the significant increase of grain size caused by wall thickness and its slight decrease connected with the distance between analyzed section and the gating system. This relationship was confirmed using statistical methods. QE22 alloy demonstrated finer grain structure than Elektron 21 alloy as well as lesser susceptibility of grain size to solidification conditions © (2012) Trans Tech Publications, Switzerland.


Dybowski B.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow | Kielbus A.,Silesian University of Technology | Cwajna J.,Silesian University of Technology
Solid State Phenomena | Year: 2012

This paper presents results of investigations on influence of pouring temperature on castability and microstructure of QE22 and RZ5 magnesium alloys. In case of QE22 alloy, the filling length of the liquid alloy increased with the increasing pouring temperature. In RZ5 no such dependence was noted. This is probably caused by oxide films in the structure of material. Grain refinement and eutectics volume fraction also didn't present correlation with pouring temperature. © (2012) Trans Tech Publications, Switzerland.


Poloczek L.,Silesian University of Technology | Dybowski B.,Silesian University of Technology | Rodak K.,Silesian University of Technology | Jarosz R.,Zm Wsk Rzeszow | Kielbus A.,Silesian University of Technology
Archives of Metallurgy and Materials | Year: 2015

Aluminium alloys are characterized by a low density, acceptable mechanical properties and good technological properties. This unique connection of features made aluminium alloys perfect structural material for the transportation industry. Also, due to their good electrical conductivity they also found application in energy production industry. High mechanical properties and electrical conductivity of the Al-Si alloys with Mg addition may be achieved by heat treatment. However, the highest mechanical properties are achieved in the early stages of age hardening - due to precipitation of coherent phases, while high electrical conductivity may be achieved only by prolonged aging, during precipitation of semi-coherent or fully noncoherent, coarse phases. Carefully heat treated AlSi7Mg alloy may exhibit both fairly high electrical conductivity and slightly increased mechanical properties. The following article present results of the research of influence of heat treatment on the properties and microstructure of sand cast AlSi7Mg alloy. Microstructure observations were performed using light microscopy, scanning electron and scanning-transmission electron microscopy. Hardness and electrical conductivity of the AlSi7Mg alloy were investigated both in as-cast condition and after heat treatment. Maximum hardness of the alloy is achieved after solutioning at 540°C for 8h, followed by 72h of aging at 150°C, while maximal electrical conductivity after solutioning at 540°C for 48h, followed by 96h of aging at 180°C. Increase of the electrical conductivity is attributed to increasing distance between Si crystals and precipitation of semi coherent phases.


Dybowski B.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow | Kielbus A.,Silesian University of Technology
Solid State Phenomena | Year: 2013

Magnesium alloys are widely used in aerospace and automotive industry due to their low density, good mechanical properties and good castability. The paper presents results of the castability tests and microstructural investigations on two unmodified magnesium casting alloys, Elektron 21 and QE22. Spirals for the castability test were poured from three temperatures: 755°C, 800°C and 835°C. Volume fraction of eutectic regions and grain size in both alloys were quantitatively evaluated. Castability increased with increasing pouring temperature. Quantity of eutectics and grain size did not show straight correlation with pouring temperature. © (2013) Trans Tech Publications, Switzerland.


Kielbus A.,Silesian University of Technology | Stopyra M.,Silesian University of Technology | Jarosz R.,ZM WSK Rzeszow
Archives of Metallurgy and Materials | Year: 2013

The paper present the influence of modifying process on chemical composition, microstructure, and selected properties of Mg alloys. Two sand-casting creep-resistant alloys, Elektron 21 and WE43, were analyzed in various forms: without modifiers, with, the amount of modifier suggested by the producer, and with this amount increased by 50% and 100%. The volume fraction of eutectic areas, tensile strength, and yield strength were measured and the fluidity and linear contraction were analyzed. The research shows that, in contrast to what is widely assumed to be a positive influence of rare-earth elements on Mg alloys properties, a large increase in the amount of modifiers does not always lead to an improvement in the alloy properties. However, the results are tentative because they may have been influenced by the melting technology used, which can be improved. Rare-earth elements tend to react with fluxes, which could lead to a decrease in mechanical properties and fluidity. More research is planned wherein the alloys are melted under a protective atmosphere.

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