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1
Content available Initial Assessment of Graphite Precipitates in Vermicular Cast Iron in the As-Cast State and after Thermal Treatments
Soiński M. S., Jakubus Aneta, Borowiecki B., Mierzwa P.
Archives of Foundry Engineering
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2021
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Vol. 21, iss. 4
131--136
EN
The purpose of the work was to determine the morphology of graphite that occurs in vermicular cast iron, both in the as-cast state and after heat treatment including austenitization (held at a temperature of 890°C or 960°C for 90 or 150 min) and isothermal quenching (i.e. austempering, at a temperature of 290°C or 390°C for 90 or 150 min). In this case, the aim here was to investigate whether the heat treatment performed, in addition to the undisputed influence of the cast iron matrix on the formation of austenite and ferrite, also affects the morphology of the vermicular graphite precipitates and to what extent. The investigations were carried out for the specimens cut from test coupons cast in the shape of an inverted U letter (type IIb according to the applicable standard); they were taken from the 25mm thick walls of their test parts. The morphology of graphite precipitates in cast iron was investigated using a Metaplan 2 metallographic microscope and a Quantimet 570 Color image analyzer. The shape factor F was calculated as the quotient of the area of given graphite precipitation and the square of its perimeter. The degree of vermicularization of graphite was determined as the ratio of the sum of the graphite surface and precipitates with F <0.05 to the total area occupied by all the precipitations of the graphite surface. The examinations performed revealed that all the heat-treated samples made of vermicular graphite exhibited the lower degree of vermicularization of the graphite compared to the corresponding samples in the as-cast state (the structure contains a greater fraction of the nodular or nearly nodular precipitates). Heat treatment also caused a reduction in the average size of graphite precipitates, which was about 225μm2 for the as-cast state, and dropped to approximately 170-200 μm2 after the austenitization and austempering processes.
2
Content available Nowoczesne materiały kompozytowe zastępujące tradycyjne materiały odlewnicze
Mierzwa P., Olejnik E., Janas A.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 1s
137--142
PL
W pracy przedstawiono możliwość przekształcenia klasycznych materiałów odlewniczych w kompozyty in situ. Materiały te znajdują coraz szersze zastosowanie w różnych gałęziach przemysłu, a szczególnie w przemyśle wydobywczym. Przekształcenie stopu klasycznego w materiał kompozytowy, wpływa wyraźnie na poprawę jego właściwości mechanicznych. W wyniku przeprowadzonych badań uzyskano nowy materiał inżynierski, który wytworzono metodą syntezy objętościowej z wykorzystaniem reakcji SHSB. Zastosowana metoda pozwala umocnić klasyczne materiały odlewnicze zarówno lokalnie, jak również objętościowo. Umocnienie to polega na syntezie cząstek ceramicznych w kąpieli metalowej, bezpośrednio w jednoetapowym procesie odlewniczym. Materiałem wyjściowym do badań było staliwo manganowe, które w wyniku przeprowadzonej reakcji syntezy, przekształcono w kompozyt typu MMCs. Fazą wzmacniającą nowego materiału były ceramiczne cząstki węglika tytanu. Prezentowane w niniejszej pracy wyniki, wskazują na znaczną poprawę zarówno właściwości mechanicznych, jak i użytkowych otrzymanego materiału kompozytowego, dotyczy to takich parametrów, jak twardości i odporności na ścieranie.
EN
The study presents an opportunity to transform the traditional casting materials into in situ composites, the latter ones being currently used on a growing scale in various sectors of the industry, especially in the extractive industries. The transformation of standard alloy into a composite considerably improves the mechanical properties. As a result of the experiment, a new engineering material was produced by the method of bulk synthesis and an SHSB reaction. The method enables hardening of the traditional casting materials, both locally and in the whole volume of the material. The hardening is obtained by the synthesis of ceramic particles in a metal bath, directly in a one-step casting process. The starting material for research was cast manganese steel which, as a result of the reaction of synthesis, was converted into an MMCs type composite. The reinforcing phase in the new material were ceramic particles of titanium carbide. The results presented in this paper show a significant improvement in both mechanical and performance properties of the composite material obtained, this also applying to parameters such as hardness and abrasive wear resistance.
3
Content available remote Effectiveness of cast iron vermicularization including 'conditioning' of the alloy
Soiński M. S., Mierzwa P.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 2
133-138
EN
The performed investigations have resulted in conclusion that the vermicularizing treatment of 'basic' cast iron, consisting in 'conditioning' the alloy by means of VLCe(2) master alloy, introducing the DENODUL5 master alloy, and graphitizing with SRF75 master alloy, provides for obtaining vermicular graphite precipitates in the structure of material cast within 15 minutes' period from the modifying treatment. The cast iron has been melted in the induction crucible furnace of medium frequency under industrial conditions. The alloy has been subjected to vermicularization in the slender ladle of 1 Mg capacity. Graphitizing has been performed in the course of transferring the cast iron from the slender ladle to the pouring ladle. A series of test coupons in the form of reversed U-blocks of test part walls 25 mm thick have been cast of the produced cast iron. Then specimens both for metallographic examination and for testing the mechanical properties have been taken from the coupons. The analysis of cast iron structure has revealed, among others, that however purely vermicular graphite precipitates occurred in specimens taken out of the lower parts of test coupon walls (which are cooled faster), the nodular graphite precipitates in quantity up to 10% could be observed in specimens from the upper parts of test coupon walls (located close beneath the sinkhead).
4
Content available remote The effect of thermal treatment on the mechanical properties of vermicular cast iron
Mierzwa P., Soiński M. S.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 1 spec.
99--102
EN
The work determines the effect of austempering (isothermal quenching) on the basic mechanical properties of cast iron with vermicular graphite. The cast iron has been produced in one of Polish foundries. Copper addition in the amount of about 1% has been introduced to the cast iron in order to obtain the pearlitic matrix. The mechanical properties (Rm, R0,2 , A5, HB) have been determined both for the as-cast state and after austenitizing at 960 °C combined with quenching at 290 °C for 90 minutes, and also after austenitizing at 960 °C followed by isothermal quenching at 290 °C for 150 minutes. It has been found that the thermal treatment, resulting in the cast iron matrix change from the ferritic-pearlitic one to the one composed of acicular precipitates of ferrite and residual austenite, causes a distinct increase in cast iron strength; after the thermal treatment it has reached about 900÷1000 MPa. The examination has been performed using the specimens cut out of the reversed U-block test coupons of walls 25 mm thick and 50 mm high.
5
Content available remote Possibilities of rationalization of the melting process proceeding in .... 700 cupola
Soiński M. S., Derda A., Skoczylas A., Zatoń B., Mierzwa P.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 1
153-156
EN
An attempt of rationalization of the cast iron melting process proceeding in a cupola has been taken on, based on the working parameters recorded during the first several hours of the cupola work. Examinations have been centred around the melting process taking place in a ... 700 hot-blast cupola with a fixed receiver (forehearth). It has been found that a significant reduction in coke consumption is possible due to changes in cupola burdening without a detriment to furnace efficiency or the temperature of molten cast iron.
6
Content available remote The low-aluminium cast iron of reduced silicon content treated with cerium mischmetal
Soiński M. S., Susek P., Hübner K., Mierzwa P.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 2
123-128
EN
The work presents the effect of cerium mischmetal used in quantities of 0.1 and 0.2 wt-% and ferrosilicon used in quantities from 0.5% to 1.5% on the alloy matrix and the shape of graphite precipitates in the low-aluminium cast iron from seven heats, basing on the examination of its structure. The hypereutectic cast iron of the relatively high carbon content (4.0÷4.2%) at the prior-to-treatment silicon and manganese content equal to ca. 0.6% and ca. 0.04%, respectively, has been examined. It has been found that the performed treatment leads to the change in the alloy matrix from the nearly almost pearlitic to the ferritic-pearlitic one accompanied by changes in the shape of graphite precipitates. Due to applying both of the mentioned substances in the above stated amounts the graphite precipitates in cast iron have taken the shape of nodular and vermicular ones, and no presence of flake graphite has been revealed. A quantitative analysis of the performed treatment i.e. determining the fractions of graphite precipitates of different shapes has been possible by means of a computer image analyser.
7
Content available remote Właściwości mechaniczne żeliwa sferoidalnego obrabianego różnymi modyfikatorami
Wilk M., Soiński M. S., Mierzwa P.
Archiwum Odlewnictwa
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2006
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R. 6, nr 18/2
33--38
PL
W artykule omówiono wyniki badań wytrzymałości na rozciąganie i wydłużenia żeliwa sferoidalnego, obrabianego czterema różnymi modyfikatorami grafityzującymi. Do modyfikacji użyto „klasycznego” żelazokrzemu oraz zapraw zawierających dodatkowo odpowiednio stront, bar lub cyrkon. Właściwości żeliwa określono na próbkach odlanych bezpośrednio po zabiegu modyfikacji grafityzującej oraz około 20 minut po tym zabiegu.
EN
Results of tensile strength and elongation examination of ductile iron treated with various inoculants have been shown in the paper. “Classic” ferrosilicon and compositions containing barium, strontium and zirconium were used. Mechanical properties directly after the modification and 20 minutes later were examined.
8
Content available remote Temperatura żeliwa wytapianego w żeliwiaku Ø600mm na zimny dmuch
Soiński M. S., Mierzwa P., Wilk M.
Archiwum Odlewnictwa
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2005
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R. 5, nr 17
273--278
PL
W artykule przedstawiono zmiany temperatury żeliwa wytapianego w żeliwiaku na zimny dmuch w początkowej fazie wytopu. Omówiono także spadek temperatury metalu związany z okresowym spuszczaniem żużla z pieca.
EN
Temperature changes of cast iron melted in a cold blast cupola in the initial phase of the melting process were shown in this paper. Temperature fall of the tapped metal connected with periodical slag removal was discussed as well.
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