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1
Content available Crystallization of Eutectics in Fe-C-V-Si Alloys
Kawalec M
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 1 spec.
143--146
EN
This article addresses the results of microstructural examinations of the volume solidifying Fe–C–V–Si alloys containing carbon in the range of 1.39÷1.76%, vanadium in the range of 6.77÷7.77% and silicon in the range of 0.02÷3.10. The melting charge was Armco iron, ferro-vanadium with 81.7 wt.%V, spectrally pure graphite and technically pure silica. It was shown that with increasing the silicon content, the microstructure of the resulting alloy changing. These changes include both a matrix the shape of the primary carbides and type of crystallizing eutectic. In the studied alloys was observed following eutectic: fibrous (crystallize as non-faceted/ non-faceted eutectic), complex regular (crystallize as faceted/ non-faceted eutectic), spiral (crystallize as faceted/ faceted eutectic). The results illustrated by the images of the microstructures made with an optical microscope and a scanning electron microscope.
2
Content available Modification of the high-alloyed white cast iron microstructure with magnesium master alloy
Kawalec M.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 2
71--74
EN
High-vanadium cast iron is the white cast iron in which the regular fibrous \gamma + VC eutectic with the volume fraction of vanadium carbide amounting to about 20% crystallises. This paper presents the results of studies on high-vanadium cast iron subjected to the inoculation treatment with magnesium master alloy. The aim of this operation is to change the morphology of the crystallising VC carbides from the fibrous shape into a spheroidal one. The study also examines the effect of the amount of the introduced inoculant on changes in the morphology of the crystallising VC carbides. To achieve the goals once set, metallographic studies were performed on high-vanadium cast iron of eutectic composition in base state and after the introduction of a variable content of the inoculant. The introduction of magnesium-based master alloy resulted in the expected changes of microstructure. The most beneficial effect was obtained with the introduction of 1.5% of magnesium master alloy, since nearly half of the crystallised vanadium carbides have acquired a spheroidal shape.
3
Content available Alloyed white cast iron with precipitates of spheroidal vanadium carbides VC
Kawalec M., Górny M.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 4
95-100
EN
The paper presents the results of tests on the spheroidising treatment of vanadium carbides VC done with magnesium master alloy and mischmetal. It has been proved that the introduction of magnesium master alloy to an Fe-C-V system of eutectic composition made 34% of carbides crystallise in the form of spheroids. Adding mischmetal to the base alloy melt caused 28% of the vanadium carbides crystallise as dendrites. In base alloy without the microstructure-modifying additives, vanadium carbides crystallised in the form of a branched fibrous eutectic skeleton. Testing of mechanical properties has proved that the spheroidising treatment of VC carbides in high-vanadium cast iron increases the tensile strength by about 60% and elongation 14 - 21 times, depending on the type of the spheroidising agent used. Tribological studies have shown that high-vanadium cast iron with eutectic, dendritic and spheroidal carbides has the abrasive wear resistance more than twice as high as the abrasion-resistant cast steel.
4
Content available Abrasive wear resistance of cast iron with precipitates of spheroidal VC carbides
Kawalec M., Olejnik E.
Archives of Foundry Engineering
|
2012
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Vol. 12, iss. 2
221-226
EN
The paper presents the results of abrasive wear resistance tests carried out on high-vanadium cast iron with spheroidal VC carbides. The cast iron of eutectic composition was subjected to spheroidising treatment using magnesium master alloy. The tribological properties were examined for the base cast iron (W), for the cast iron subjected to spheroidising treatment (S) and for the abrasion-resistant steel (SH). Studies have shown that high-vanadium cast iron with both eutectic carbides and spheroidal carbides has the abrasion resistance twice as high as the abrasion-resistant cast steel. The spheroidisation of VC carbides did not change the abrasion resistance compared to the base high-vanadium grade.
5
Content available Forming of the microstructure in Fe-C-V alloys
Kawalec M., Fraś E.
Metallurgy and Foundry Engineering
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2011
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Vol. 37, no. 1
17-24
EN
The study presents the results of microstructural examinations of the volume solidifying Fe-C-V alloys containing carbon in the range of 1.45-2.23% and vanadium in the range of 7.33-15.08%. Attention was focussed on near-eutectic alloys. The Fe-C-V eutectic crystallising in these alloys is composed of ferrite and vanadium carbides of VC1-x type, and as such is included in the group of fibrous eutectics. During research, the experimental eutectic lines were plotted for Fe-C-V alloys, and a formula enabling calculation of the eutectic saturation ratio of these alloys was proposed.
PL
W pracy przedstawiono wyniki badań mikrostruktury stopów Fe-C-V, o zawartości węgla w zakresie 1,45-2,23% i wanadu w zakresie 7,33-15,08%, krystalizujących w sposób objętościowy, przy czym szczególną uwagę zwrócono na stopy okołoeutektyczne. Krystalizująca w stopach Fe-C-V eutektyka składa się z ferrytu i węglików wanadu typu VC1-x i jest zaliczana do grupy eutektyk włóknistych. W pracy określono eksperymentalnie przebieg linii eutektycznej dla stopów Fe-C-V oraz wyznaczono zależność na stopień nasycenia eutektycznego dla tych stopów.
6
Content available The spheroidisation of VC carbides in high-vanadium cast iron
Kawalec M.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 3 spec.
111--116
EN
High-vanadium cast iron is a type of white cast iron, in which a regular fibrous γ + VC eutectic with about 20 vol.% of vanadium carbides crystallises. The paper presents the results of research during which the high-vanadium cast iron was subjected to spheroidisation treatment with magnesium Elmag 5800 master alloy. The purpose of this operation was to obtain the VC carbides of a spheroidal shape. The study also included metallographic examinations and testing of mechanical properties carried out on high-vanadium cast iron of a eutectic composition in as-cast condition and after the spheroidising treatment. The attempt to spheroidise the vanadium carbides has proved to be quite successful. The introduction of magnesium alloy has made nearly one half of the crystallised vanadium carbides acquire a spheroidal shape. The, obtained in this way, high-vanadium cast iron with vanadium carbides of a spheroidal shape showed very high mechanical and plastic properties. The tensile strength Rm increased by 60% compared to the as-cast alloy, while ductility increased more than twenty times. The presented results are based on the initial trials, but further studies of this new material are planned, mainly to check its resistance to abrasion, to impacts and corrosion. Tests are also planned to increase the fraction of spheroidal carbides and measure the effect of their content on the mechanical and tribological properties.
7
Content available remote Shaping of the microstructure in neareutectic Fe-C-V alloys
Kawalec M., Fraś E.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 4
83--88
EN
The study presents the results of microstructural examinations of the volume solidifying Fe-C-V alloys containing carbon in the range of 1.45÷2.23% and vanadium in the range of 7.33÷15.08%. Attention was focussed on near-eutectic alloys. The Fe-C-V eutectic crystallising in these alloys is composed of ferrite and vanadium carbides of VC1-x type, and as such is included in the group of fibrous eutectics. During research, the experimental eutectic lines were plotted for Fe-C-V alloys, and a formula enabling calculation of the eutectic saturation ratio of these alloys was proposed.
8
Content available remote Wpływ krzemu na strukturę żeliwa wysokowanadowego
Kawalec M., Fraś E.
Archiwum Odlewnictwa
|
2006
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R. 6, nr 21/1
389-394
PL
W pracy przedstawiono wyniki badań mikrostruktury stopów Fe-C-V oraz Fe-C-V-Si, krystalizujących w sposób objętościowy, o zawartości węgla w zakresie 1,5%, wanadu w zakresie 15-17% i krzemu w zakresie 1-3%. Powstająca w stopach Fe-C-V eutektyka, składa się z ferrytu i węglików wanadu typu VC1-x, i jest zaliczana do grupy eutektyk włóknistych. Wprowadzanie do układu Fe-C-V dodatków krzemu zmienia geometrię krystalizujęcej eutektyki z włóknistej na złożoną regularnie oraz węglików pierwotnych w postaci dendrytów nieściano-nieścanowych na dendryty ścianowe.
EN
In the paper microstructural evaluation of Fe-C-V as well as Fe-C-V-Si alloys are made. Volumetric solidification of alloys containing of carbon: 1,5%, vanadium: 7–15% and silicon 1–3% was studied. In particular, effect of silicon on primary and secondary microstructure these alloys has been investigated. It was stated that silicon changes kind of eutectic from fiber nonfaceted-nonfaceted to complex regular and morphology of primary carbides from nonfaceted dendrites to faceted dendrites.
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