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.
An initial assessment of the effectiveness of cast iron inoculation, performed by the method of impulse introducing the master alloy into
cast iron, is presented. The experiment was concerned with the hypoeutectic gray cast iron inoculated with either the Alinoc or the Barinoc
master alloy by means of an experimental device for pneumatic transportation. Examinations involved pneumatic injection of the
powdered inoculant carried in a stream of gaseous medium (argon) into the metal bath held in the crucible of an induction furnace. It was
found that the examined process is characterised by both high effectiveness and stability.
The paper presents data concerning the total production of castings over the 2000-2014 period, both on a global scale, and in Poland. The
basic types of casting alloys were taken into account. Changes in the production volume and structure over the period of the analysed 15
years were pointed out with respect to countries leading in foundry production. The topmost position in the world foundry industry is held
by China for several years (with almost 45% share in the foundry market), the second place is taken by India (with almost 9% share). A
distinct reduction in the shares of the once significant producers of castings, such as USA, Japan, Germany, Russia, Italy, or France, was
observed over the 2000-2014 period. Poland had a share of 1.16% in 2000, and of 1.02% in 2014. Comparing the detailed data concerning
the years 2000 and 2014, one can see that the fractions of castings made of ductile iron, cast steel, aluminium alloys, or magnesium alloys
increase on a global scale, while such alloys as grey cast iron or malleable are in decline.
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.
The work determined the influence of aluminium in the amount from about 0.6% to about 8% on graphitization of cast iron with
relatively high silicon content (3.4%-3.9%) and low manganese content (about 0.1%). The cast iron was spheroidized with cerium mixture
and graphitized with ferrosilicon. It was found that the degree of graphitization increases with an increase in aluminium content in cast
iron up to 2.8%, then decreases. Nodular and vermicular graphite precipitates were found after the applied treatment in cast iron containing
aluminium in the amount from about 1.9% to about 8%. The Fe3AlCx carbides, increasing brittleness and deteriorating the machinability of
cast iron, were not found in cast iron containing up to about 6.8% Al. These carbides were revealed only in cast iron containing about 8% Al.
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%.
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.
The study presents a concept of generation of micro-cracks (or cracks) in metal specimens in order to assess their material with respect to the thermal shock resistance. Both the method of conducting the experiment and the criteria of the assessment of the material resistance to the rapid temperature changes are discussed. The schematic diagram of the research stand used for repeated heating and rapid cooling of specimens, constructed in the Foundry Institute of the Częstochowa University of Technology, is presented. The proposed solution enables to maintain constant conditions of the experiment. The tests were held for flat specimens 70 mm long, 20 mm wide, and 5 mm thick, tapered over a distance of 15 mm towards both ends. The specimens were induction heated up to the specified temperature and then, in response to the signal produced by a pyrometer, dipped in the tank containing the cooling medium. The thermal shock resistance of the material can be assessed on the basis of either the total length of the micro-cracks arisen at the tapered parts of a specimen after a specified number of heating-and-cooling cycles, or the number of such cycles prior to the total damage of a specimen, or else the number of thermal cycles prior to generation of the first crack. The study includes an exemplary view of the metal specimen after the thermal shock resistance tests, as well as the illustrative microstructure of the vermicular cast iron which reveals a crack propagating from the edge towards the core of the material.