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1
Content available Initial Analysis of the Surface Layer of AVGI Cast Iron Subject to Abrasion
Jakubus Aneta
Archives of Foundry Engineering
|
2022
|
Vol. 22, iss. 2
50--56
EN
The article presents the results of research on the abrasion resistance of cast iron with vermicular graphite in the as-cast state and after austempering (the latter material is referred to as AVGI – Austempered Vermicular Graphite Iron). Austenitization was carried out at the temperature values of either 900°C or 960°C, and austempering at the temperature values of either 290°C and or 390°C. Both the austenitization and the austempering time was equal to 90 minutes. The change of the pearlitic-ferritic matrix to the ausferritic one resulted in an increase in mechanical properties. Abrasion tests were conducted by means of the T-01M pin-on-disc tribometer. The counter-sample (i.e. the disc) was made of the JT6500 friction material. Each sample was subject to abrasion over a sliding distance of 4000 m. The weight losses of both samples and counter-samples were determined by the gravimetric method. It was found that the vermicular cast iron austenitized at 900°C and austempered at 290°C was characterized by the lowest wear among the evaluated cast iron types. The geometric structure of the surface layer after the dry friction test exhibited irregular noticeable grooves, distinct oriented abrasion traces, plastic flow of the material, microcracks, and pits generated by tearing out the abraded material. The largest surface roughness was found for the AVGI cast iron heat-treated according to the variant 3 (Tγ =900 ºC; Tpi = 390°C), while the smallest one occurred in AVGI cast iron subject to either the variant 2 (Tγ =960 ºC; Tpi = 290°C) or the variant 4 (Tγ =900 ºC; Tpi = 290°C) of heat treatment and was equal to either 2.5 μm or 2.66 μm, respectively. It can be seen that the surface roughness decreases with the decrease in the austempering temperature.
2
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
|
2021
|
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.
3
Content available Influence of Microstructure and Heat Transfer Surface on the Thermal Power of Cast Iron Heat Exchangers
Mróz M., Orłowicz A. W., Tupaj M., Lenik M., Kawiński M. J., Kawiński M.
Archives of Foundry Engineering
|
2021
|
Vol. 21, iss. 4
93--96
EN
The paper presents the results of calorimetric tests of segment elements of fireplace inserts. The aim of the work was to optimize their thermal power by replacing the previously used gray cast iron with flake graphite with gray iron with vermicular graphite and replacing the existing geometry of the heat transfer surface with a more developed one. It turned out that the thermal power of the test segments made of cast iron with vermicular graphite was higher compared to the segments of the same shape made of gray cast iron with flake graphite. It was found that the use of segments made of vermicular cast iron with a ferritic matrix allowed for an increase in the thermal power value by dozen percent, compared to segments of the same shape made of vermicular cast iron with a pearlitic matrix. The test results showed that the thermal power of the test segments depends on the variant of the development of both the heat receiving surface and the heat giving off surface. The highest value of the thermal power was obtained when ribbing in the form of a lattice was used on both of these surfaces, and the lowest when using flat surfaces.
4
Content available Ultrasonic Testing of Vermicular Cast Iron Microstructure
Tupaj M., Orłowicz A. W., Mróz M., Kupiec B., Pająk D., Kawiński M.
Archives of Foundry Engineering
|
2020
|
Vol. 20, iss. 4
36--40
EN
The paper presents results of a study on the effect of passage of time on magnesium content in iron alloys and the effect of magnesium content on the number of vermicular graphite precipitations per unit surface area and value of the longitudinal ultrasonic wave velocity for two different vermicularization methods. The study was carried out with the use of inspection bar castings. For specific production conditions, it has been found that in case of application of both the cored wire injection method and the method of pouring liquid metal over magnesium master alloy on ladle bottom, the satisfactory level of magnesium content in the bottom-pour ladle, for which it was still possible to obtain castings with vermicular graphite, was 0.018% Mg. In case of the cored wire injection method, the “time window” available to a pouring station at which castings of vermicular cast iron are expected to be obtained, was about 5 minutes. This corresponds to the longitudinal ultrasonic wave velocity values exceeding 5500 m/s and the number of graphite precipitations per unit surface area above 320 mm-2. In case of the master alloy method, the respective “time window” allowing to obtain castings of vermicular cast iron was only about 3 minutes long. This corresponds to the longitudinal ultrasonic wave velocity value above 5400 m/s and the number of graphite precipitations per unit surface area above 380 mm-2.
5
Content available The Influence of the Shape of Graphite Precipitates on the Cast Iron Abrasion Resistance
Jakubus A., Soiński M. S.
Archives of Foundry Engineering
|
2019
|
iss. 4
87--90
EN
The paper presents the initial results of investigation concerning the abrasion resistance of cast iron with nodular, vermicular, or flake graphite. The nodular and vermicular cast iron specimens were cut out of test coupons of the IIb type with the wall thickness equal to 25 mm, while the specimens made of grey cast iron containing flake graphite were cut out either of special casts with 20 mm thick walls or of the original brake disk. The abrasion tests were carried out by means of the T-01M tribological unit working in the pin-on-disk configuration. The counterface specimens (i.e. the disks) were made of the JT6500 brand name friction material. Each specimen was abraded over a distance of 4000 m. The mass losses, both of the specimens and of the counterface disks, were determined by weighting. It was found that the least wear among the examined materials was exhibited by the nodular cast iron. In turn, the smallest abrasion resistance was found in vermicular cast iron and in cast iron containing flake graphite coming from the brake disk. However, while the three types of specimens (those taken from the nodular cast iron and from grey cast iron coming either from the special casts or from the brake disk) have almost purely pearlitic matrix (P95/Fe05), the vermicular cast iron matrix was composed of pearlite and ferrite occurring in the amounts of about 50% each (P50/Fe50). Additionally, it was found that the highest temperature at the cast iron/counterface disk contact point was reached during the tests held for the nodular cast iron, while the lowest one occurred for the case of specially cast grey iron.
6
Badania w Odlewni Żeliwa METALPOL nad opracowaniem technologii wytwarzania żeliwa wermikularnego techniką PE z użyciem pręta hybrydowego
Dyrlaga M., Zych J., Bahuon O.
Przegląd Odlewnictwa
|
2017
|
Vol. 67, nr 7-8
280--285
7
Wytwarzanie odlewów z żeliwa wermikularnego w technologii Inmold na liniach formierskiej z poziomą płaszczyzną podziału
Zych J., Żyrek A.
Przegląd Odlewnictwa
|
2014
|
Vol. 64, nr 3-4
94--104
PL
W pracy przedstawiono technologię otrzymywania żeliwa wermikularnego w metodzie Inmold. Opracowano procedurę i zasady projektowania komór reakcyjnych, obliczania i doboru parametrów konstrukcyjnych układu wlewowego, doboru zaprawy magnezowej i jej granulacji. Przeprowadzono szereg badań polegających na weryfikacji i dopracowaniu schematu postępowania w trakcie projektowania procesu technologicznego Inmold. Osiągnięto produkcyjną powtarzalność w uzyskiwaniu założonych właściwości mechanicznych żeliwa wermikularnego na linii BMD. Wyniki badań mają charakter utylitarny.
EN
The paper presents the so called Inmold technology for obtaining vermicular cast iron. A procedure and principles have been developed to design reaction chambers, determine and select construction parameters for pouring systems, and to select magnesium mortars and their granulations. A series of tests have been carried out to verify and improve the designing procedures for the Inmold technological processes. The tests have shown production repeatability as regards obtaining the required mechanical properties of vermicular cast iron on the BMD moulding lines. The results are of utilitarian nature.
8
Content available The structure and mechanical properties of pearlitic-ferritic vermicular cast iron
Guzik E., Kopyciński D., Kleingartner T., Sokolnicki M.
Archives of Foundry Engineering
|
2012
|
Vol. 12, iss. 1
33-36
EN
The results of studies on the use of magnesium alloy in modern Tundish + Cored Wire injection method for production of vermicular graphite cast irons were described. The injection of Mg Cored Wire length is a treatment method which can be used to process iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire for the production of vermicular graphite cast irons at the; Tundish + Cored Wire to be injected methods (PE) for pearlitic-ferritic matrix GJV with about 25 % ferrite content. The results of calculations and experiments have indicated the length of the Cored Wire to be injected basing on the initial sulfur content and weight of the treated melt. The paper presents a microstructure matrix and vermicular graphite in standard sample and different walled castings. The results of numerous trials have shown that the magnesium Tundish + PE Method process can produce high quality vermicular graphite irons under the specific industrial conditions of the above mentioned foundries.
9
Content available Preparation vermicular graphite in thin and thick wall iron castings
Kopyciński D., Guzik E., Nowak A., Ronduda M., Sokolnicki M.
Archives of Foundry Engineering
|
2012
|
Vol. 12, iss. 2
41-44
EN
The results of studies on the use of magnesium alloy in modern Tundish for production of vermicular graphite cast irons were described. This paper describes the results of using a low-magnesium ferrosilicon alloy for the production of vermicular graphite cast irons. The paper presents a vermicular (and nodular) graphite in different walled castings. The results of trials have shown that the magnesium Tundish process can produce high quality vermicular graphite irons under the specific industrial conditions of Foundries - Odlewnie Polskie S.A. in Starachowice. In this work describes too preliminary studies on the oxygen state in cast iron and their effect on graphite crystallization.
10
Content available Vermicular cast iron production in the “Inmold” technology (in the Metalpol casting house) and the assessment of its thermal fatigue resistance
Zych J., Żyrek A.
Archives of Foundry Engineering
|
2011
|
Vol. 11, iss. 3 spec.
255--260
EN
The method of obtaining the vermicular cast iron in the “Inmold” technology and the results of the thermal fatigue investigations, are presented in the paper. The influence of the maximum cycle temperature (Tmax) on the thermal fatigue resistance was examined by means of the L.F. Coffin method. The cast iron structure change caused by the thermal fatigue is presented in the paper. When the vermicular cast iron is subjected to the thermal fatigue the matrix ferritisation occurs, which leads to the strength, Rm., decrease. The heating process of the vermicular cast iron is slower as compared to the spheroidal cast iron, whereas the cooling process is faster. Under the same conditions of heat exchanging the vermicular cast iron is heated to a much lower temperature than the spheroidal one. Together with the maximum heating temperature increase the thermal fatigue resistance decreases.
11
Content available remote Morphology of graphite precipitates in austenitic ductile iron
Zarębski K., Putyra P., Khatemi B., Tabor A.
Archives of Foundry Engineering
|
2011
|
Vol. 11, iss. 2
149-152
EN
The final mechanical properties of cast iron depend on the nature and properties of the matrix and on the morphology of graphite precipitates. The article presents the results of studies of the structure of austenitic ductile iron with different nickel content. The studies include the identification and stereological description of graphite precipitates. The volume fraction of graphite in cast iron was determined in function of the size of the precipitates and the adopted shape coefficient of single particles, enabling the content of regular spheroids to be estimated.
12
Content available remote Effectiveness of cast iron vermicularization including 'conditioning' of the alloy
Soiński M. S., Mierzwa P.
Archives of Foundry Engineering
|
2011
|
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).
13
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
|
2010
|
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.
14
Content available remote Structure and mechanical properties as well as application of high quality vermicular cast iron
Guzik E.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 3
95--100
EN
The results of studies on the use of magnesium alloy in modern cored wire injection method and Tundish for production of vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 55%) for the production of high quality vermicular graphite cast irons at foundry. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The paper presents a microstructure matrix and vermicular graphite in standard sample and castings with different wall thickness. The results of numerous trials have shown that the magnesium cored wire process can produce high quality vermicular graphite with ferritic-pearlite and pearlitic-ferrite matrix irons under the specific industrial conditions.
15
Content available remote Structure and mechanical properties of vermicular cast iron in cylinder head casting
Guzik E., Dzik S.
Archives of Foundry Engineering
|
2009
|
Vol. 9, iss. 1
175-180
EN
The paper discusses the problem of grain density and ferrite content in microstructure of vermicular graphite iron cast in bars of different section diameters and cylinder head casting. The experimental results regarding the section effect demonstrate that the nodule count, grain density and ferrite content are all function of the cast bar diameter in this particular case ranging from 0.6 to 8.0 cm and microstructure and mechanical properties in the cylinder head. The nodule count (or grain density) has been reported to increase, while ferrite content was decreasing with decreasing casting diameter. The density number of the grains Nv has been related (by regression analysis) to the undercooling degree [...]. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 40%) for the production of vermicular graphite cast irons at 'WSK-Rzeszów' Metallurgical Plant Ltd. for first series of cylinder head. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The paper presents a microstructure matrix and vermicular graphite in standard sample and different walled cylinder head castings. The results of numerous trials have shown that the magnesium cored wire process can produce high quality vermicular graphite irons, which its ideally suited to meet the current and future requirements of engine design and performance.
16
Content available remote A study on the structure and mechanical properties of vermicular cast iron with pearlitic-ferritic matrix
Guzik E., Kleingartner T.
Archives of Foundry Engineering
|
2009
|
Vol. 9, iss. 3
55-60
EN
The results of studies on the use of magnesium alloy in modern cored wire injection method for production of vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 45%) for the production of vermicular graphite cast irons at Giesserei Heunisch GmbH Foundry with the pearlite matrix with about 20% ferrite content. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The paper presents a microstructure matrix and vermicular graphite in standard sample and different walled castings. The results of numerous trials have shown that the magnesium cored wire process can produce high quality vermicular graphite irons under the specific industrial conditions of the above mentioned foundries.
17
Azotowanie jarzeniowe żeliwa wermikularnego w aspekcie wzrostu odporności na zużycie przez tarcie
Sobiecki J.R., Wierzchoń T.
Inżynieria Powierzchni
|
2008
|
Nr 4
16-20
PL
W artykule przedstawiono wpływ azotowania w warunkach wyładowania jarzeniowego żeliwa wermikularnego na mikrostrukturę i właściwości użytkowe takie jak mikrotwardość i odporność na zużycie przez tarcie. Zastosowanie temperatury azotowania 580°C w czasie 8 godzin prowadzi do wytworzenia strefy związków o grubości około 8 žm i strefy dyfuzyjnej o grubości ponad 200 žm. Azotowanie zdecydowanie obniża zużycie Liniowe żeliwa jak również intensywność zużycia, co skutkuje podwyższeniem odporności na zużycie przez tarcie. Po procesie azotowania jarzeniowego obserwuje się kilkukrotne zmniejszenie początkowego i końcowego współczynnika tarcia. Mikrotwardość powierzchniowa wzrasta do wartości 570 HV 0,05.
EN
It is discussed in the paper glow-discharge assisted nitriding of vermicular cast iron affect the microstructure, and useful properties like microhardness and wear resistance. The application of 580°C during 8 hours of experiment results in 8 žm of compound lager and above 200 žm the diffusion zone. Plasma nitriding process significantly decreases the linear wear and the wear intensity of the substrate and increases the wear resistance. It also reduces the value of initial and final friction coefficients several limes. The microhardness increases to the 570 HV 0,05.
18
Content available remote The influence of cooling rate on the hardness of cast iron with nodular and vermicular graphite
Soiński M. S., Zatoń B., Skoczylas A., Derda A.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 4
199-204
EN
The paper presents hardness changes for cast iron with nodular and vermicular graphite, determined within the separately cast test blocks. Investigation has comprised cast irons with similar ferrite and pearlite fractions in the metal matrix. The hardness measurements have been performed by Brinell method for samples taken both from an edge and from the centre of a Y block (for nodular cast iron) or of a reversed U block (in the case of vermicular cast iron). Investigations have pertained both to the test parts and to the sinkheads of the test blocks. Hardness measurements have been completed with metallographic examination.
19
Content available remote Application of cored wire injection method to the producing of vermicular cast iron
Guzik E., Kleingartner T.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 1 spec.
127--130
EN
The results of studies on the use of magnesium alloy in modern cored wire injection method for production of vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 45% ) for the production of vermicular graphite cast irons at Giesserei Heunisch GmbH Foundry. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The paper presents a microstructure matrix and vermicular graphite in standard sample and different walled castings. The results of numerous trials have shown that the magnesium cored wire process can produce high quality vermicular graphite irons under the specific industrial conditions of the above mentioned foundries.
20
Content available remote Analysis of quality and cost of FeSiMg treatment master alloy vs. cored wire in production of ductile cast iron
Guzik E.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 2
45-48
EN
The results of studies on the use of FeSi5%Mg magnesium alloy in modern cored wire injection method for production of nodular and vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process The injection of Mg cored wire length is a treatment method which can be used to process iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 47-70%) for the production of vermicular and nodular graphite cast irons at in at least 13 foundries. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The results of numerous trials have shown that the magnesium cored wire process can produce high quality nodular and vermicular graphite irons under the specific industrial conditions of the above mentioned foundries. It has also been proved that in the manufacture of nodular graphite iron, the cost of the nodulariser in the form of elastic cored wire is lower than the cost of the FeSiMg5 master alloys.
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