Wyniki wyszukiwania - BazTech

1

Assessment of the Quality of Ductile Cast Iron EN-GJS-500-7 Through the Influence of its Chemical Composition on the Grain Composition of Spheroidal Graphite

Pacha-Gołębiowska Halina

Archives of Foundry Engineering

|

2022

|

Vol. 22, iss. 4

85--89

EN

Quantitative evaluation of the microstructure obtained in a product is nowadays commonly required both in R&D activities and during routine quality control of materials and components. This paper presents an assessment of the quality of ductile cast iron, based on investigations of the effect of chemical composition on the distribution of ductile graphite precipitates in low-alloy cast iron EN-GJS-500-7. The size of graphite precipitates was expressed in terms of equivalent cross-sectional diameter, which made it possible to describe the distribution of graphite precipitates with a function simulating the log-normal distribution of graphite. The resulting U, W and Z parameters were statistically analysed, including the effect of chemical composition on graphite distribution. In the studied cast iron, the components that increase the U parameter are silicon, manganese and phosphorus, thus favourably affecting the total graphite number. In contrast, the constituents that decrease the U parameter are carbon, chromium and aluminium.

2

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

Thermal Shock Resistance of Cast Iron with Various Shapes of Graphite Precipitates

Jakubus A., Soiński M. S.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 2

121--124

EN

The influence of a shape of graphite precipitates in cast iron on the thermal shock resistance of the alloy was initially determined. Investigations included the nodular cast iron and the vermicular one, as well as the cast iron containing flake graphite. The thermal shock resistance was examined at a special laboratory stand which allowed for multiple heating and cooling of specimens within the presumed temperature range. The specimens were inductively heated and then cooled in water of constant temperature of about 30°C. There were used flat specimens 70 mm long, 5 mm thick in the middle part, and tapering like a wedge over a distance of 15 mm towards both ends. The total length of cracks generated on the test surfaces of the wedge-shaped parts of specimens was measured as a characteristic value inversely proportional to the thermal shock resistance of a material. The specimens heated up to 500°C were subjected to 2000 test cycles of alternate heating and cooling, while the specimens heated up to 600°C underwent 1000 such cycles. It was found that as the heating temperature rose within the 500-600°C range, the thermal shock resistance decreased for all examined types of cast iron. The research study proved that the nodular cast iron exhibited the best thermal shock resistance, the vermicular cast iron got somewhat lower results, while the lowest thermal shock resistance was exhibited by grey cast iron containing flake graphite.

4

Investigations of Ferritic Nodular Cast Iron Containing About 5-6% Aluminium

Soiński M. S., Kordas P., Skurka K., Jakubus A.

Archives of Foundry Engineering

|

2016

|

Vol. 16, iss. 4

141--146

EN

The work presents results of investigations concerning the production of cast iron containing about 5-6% aluminium, with the ferritic matrix in the as-cast state and nodular or vermicular graphite precipitates. The examined cast iron came from six melts produced under the laboratory conditions. It contained aluminium in the amount of 5.15% to 6.02% (carbon in the amount of 2.41% to 2.87%, silicon in the amount of 4.50% to 5.30%, and manganese in the amount of 0.12% to 0.14%). After its treatment with cerium mixture and graphitization with ferrosilicon (75% Si), only nodular and vermicular graphite precipitates were achieved in the examined cast iron. Moreover, it is possible to achieve the alloy of pure ferritic matrix, even after the spheroidizing treatment, when both the aluminium and the silicon occur in cast iron in amounts of about 5.2÷5.3%.

5

Characteristics of Graphite Precipitates in Aluminium Cast Iron Treated with Cerium Mixture

Soiński M. S., Jakubus A., Kordas P., Skurka K.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 1

93--98

EN

The work determined the influence of aluminium in the amount from about 1% to about 7% on the graphite precipitates in cast iron with relatively high silicon content (3.4% to 3.90%) and low manganese content (about 0.1%). The cast iron was spheroidized with cerium mixture and graphitized with ferrosilicon. The performed treatment resulted in occurring of compact graphite precipitates, mainly nodular and vermicular, of various size. The following parameters were determined: the area percentage occupied by graphite, perimeters of graphite precipitates per unit area, and the number of graphite precipitates per unit area. The examinations were performed by means of computer image analyser, taking into account four classes of shape factor. It was found that as the aluminium content in cast iron increases from about 1.1% to about 3.4%, the number of graphite precipitates rises from about 700 to about 1000 per square mm. For higher Al content (4.2% to 6.8%) this number falls within the range of 1300 – 1500 precipitates/mm2. The degree of cast iron spheroidization increases with an increase in aluminium content within the examined range, though when Al content exceeds about 2.8%, the area occupied by graphite decreases. The average size of graphite precipitates is equal to 11-15 μm in cast iron containing aluminium in the quantity from about 1.1% to about 3.4%, and for higher Al content it decreases to about 6 μm.

6

The influence of small amounts of aluminium on the effectiveness of cast iron spheroidization with magnesium

Soiński M. S., Jakubus A.

Archives of Foundry Engineering

|

2013

|

Vol. 13, iss. 3

80--83

EN

The influence of aluminium added in amounts of about 1.6%, 2.1%, or 2.8% on the effectiveness of cast iron spheroidization with magnesium was determined. The cast iron was melted and treated with FeSiMg7 master alloy under industrial conditions. The metallographic examinations were performed for the separately cast rods of 20 mm diameter. They included the assessment of the shape of graphite precipitates and of the matrix structure. The results allowed to state that the despheroidizing influence of aluminium (introduced in the above mentioned quantities) is the stronger, the higher is the aluminium content in the alloy. The results of examinations carried out by means of a computer image analyser enabled the quantitative assessment of the considered aluminium addition influence. It was found that the despheroidizing influence of aluminium (up to about 2.8%) yields the crystallization of either the deformed nodular graphite precipitates or vermicular graphite precipitates. None of the examined specimens, however, contained the flake graphite precipitates. The results of examinations confirmed the already known opinion that aluminium widens the range of ferrite crystallization.

7

The Influence of Aluminium on the Spheroidization of Cast Iron Assessed on the Basis of Wedge Test

Soiński M. S., Jakubus A., Stradomski G.

Archives of Foundry Engineering

|

2013

|

Vol. 13, iss. 1 spec.

163--168

EN

The paper discusses the influence of aluminium in quantities from about 1.9% to about 4.7% on both the alloy matrix and the shape of graphite precipitates in cast iron spheroidized with cerium mixture (added in the quantity of 0.11%) and inoculated with ferrosilicon (1.29%). The metallographic examinations were carried out for specimens cut out of the wedge test castings (22 mm base width, 120 mm height, 180 mm length) halfway along their length. It was found that the highest susceptibility to graphitization exhibits the cast iron containing about 2.8% Al. The alloy matrices were classified and the degrees of graphite spheroidization were determined. Microscopic observations were carried out along the wedge test casting height at several places, the first distant by 20 mm from the specimen apex, the next ones every 20 mm farther. Precipitates of nodular and vermicular graphite were found in the cast iron structure. The results of examination allow to state that cast iron spheroidized in the way described here is characterised by the degree of spheroidization which increase with an increase in aluminium content within the examined range.

8

The influence of small amounts of aluminium on the spheroidization of cast iron with cerium mischmetal

Soiński M. S.

Archives of Foundry Engineering

|

2012

|

Vol. 12, iss. 2

117-122

EN

The influence of aluminium (added in quantity from about 0.6% to about 2.8%) on both the alloy matrix and the shape of graphite precipitates in cast iron treated with a fixed amounts of cerium mischmetal (0.11%) and ferrosilicon (1.29%) is discussed in the paper. The metallographic examinations were carried out for specimens cut out of the separately cast rods of 20 mm diameter. It was found that the addition of aluminium in the amounts from about 0.6% to about 1.1% to the cast iron containing about 3% of carbon, about 3.7% of silicon (after graphitizing modification), and 0.1% of manganese leads to the occurrence of the ferrite-pearlite matrix containing cementite precipitates in the case of the treatment of the alloy with cerium mischmetal . The increase in the quantity of aluminium up to about 1.9% or up to about 2.8% results either in purely ferrite matrix in this first case or in ferrite matrix containing small amounts of pearlite in the latter one. Nodular graphite precipitates occurred only in cast iron containing 1.9% or 2.8% of aluminium, and the greater aluminium content resulted in the higher degree of graphite spheroidization. The noticeable amount of vermicular graphite precipitates accompanied the nodular graphite.

9

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).

10

Krytyczna ocena międzynarodowej znormalizowanej klasyfikacji cech wydzieleń grafitu w żeliwie

Piaskowski J.

Odlewnictwo - Nauka i Praktyka

|

2003

|

R. 5, nr 5

38-50

11

Struktura żeliwa nadeutektycznego modyfikowanego kompleksowo dodatkami zawierającymi bizmut i cer.

Warchala T., Soiński M.S.

Archiwum Nauki o Materiałach

|

2001

|

T. 22, nr 2

145-157

PL

W artykule omówiono wyniki badań nad wpływem małych dodatków bizmutu (od 0,0006% do 0,0017%) i ceru (od 0,010% do 0,043%), wprowadzonych jako modyfikatory do żeliwa nadeutektycznego (Sc od 1,02 do 1,09), na charakterystyki grafitu oraz udział ferrytu w osnowie. Stwierdzono, że następuje zmniejszenie udziału grafitu, obwodu i liczby jego wydzieleń oraz zmiana postaci z płatkowej na zwartą. Udział ferrytu w osnowie wzrasta z udziału śladowego do ponad 80%. Optymalny pozimo zawartości bizmutu wynosi od 0,0007% do 0,0010%. Udział ceru powinien odpowiadać stosunkowi Ce/Bi w granicach 25-50.

EN

The paper discusses results of investigation concerning the influence of small additions of bismuth (from 0,0006% to 0,0017%) and cerium (from 0,010% to 0,043%) introduced as modifiers into the hypereutectic cast iron (Sc from 1,02 to 1,09) on the graphite characteristics and the fraction of ferrite in the matrix. Having performed the statistic analysis of experimental results, the authors have graphically determined the relationships between the bismuth and cerium content and the examined structure parameters. It has been found that the graphite percentage has decreased, as well as the total perimeter, the number of its precipitates, and the shape of graphite changes from flake to compact ones. The ferrite in the matrix increases from trace amounts to over 80%. It has been also noticed that for the hypereutectic cast iron the advantageous changes in the parameters of structure are related to the proportion of cerium to bismuth content. The optimum level of bismuth content falls within in range from 0,0007% to 0,0010%. The cerium should correspond to the Ce/Bi proportion equal to 25-50.