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

Abstract

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%.

Structural characterization and mechanical properties of rotary melting furnace processed aluminium alloyed ductile irons

“…In addition, due to the increased nucleation sites for graphite precipitation and their distribution in the matrix, the growing graphite nodules may impinge on one another, resulting in non-sphericity of the graphite. Hence the explanation for some vermicular type graphite also observed in the ductile irons [12].…”

“…Precisely, it can be seen from Table 4 that ductile iron compositions containing 3.02 and 3.74 wt.% Al had higher pearlite contents of 55.95 and 66.40%, respectively. Both compositions were also linked with low nodules volume fraction, which implies that though the nodules count are more, they are relatively smaller in size which is a direct effect of Al on the Fe-C-Al alloy system [12].…”

“…Apart from being a relatively low-cost metallic material, Al serves as a graphitizer in cast iron and thus helps in the development of carbide free pearlite matrix and high nodules count [7][8][9]. Al equally, increases the eutectoid temperature of cast irons, thereby increasing the allowable working temperatures [10][11][12]. The achievement of these microstructural features in cast irons, which are relevant to the improvement of mechanical properties and oxidation and corrosion resistance [13][14], are reported to be dependent on processing factors, and thus the same outcomes are not guaranteed when process factors are altered.…”

Microstructural Characteristics, Mechanical and Wear Behaviour of Aluminium-Alloyed Ductile Irons Subjected to Two Austempering Processes

“…Al is a relatively cheap and readily accessible metallic material and its use in the development of Al-alloyed ductile irons have been found applicable in automobile component design. The use of Al as alloying addition in ductile irons has been reported to have the potentials of improving machinability, high strength and good toughness, improved fatigue and wear resistance, as well as enhanced heat and fire resistance [1][2][3][4][5][6]. The improved properties are achieved because Al is a graphitizer and acts by increasing the eutectoid temperature of cast irons, thereby increasing the allowable working temperature [1,5,7,8].…”

The Initial Assessment of Effectiveness of the Impulse Method of Introducing an Inoculant into Cast Iron

“…This additions increase the number of active nuclei of graphite crystallization, thus increasing the nucleation ability of the alloy [1]. Popular methods of adding the inoculants, applied in foundry practice, are: inoculation performed in a ladle; the on-stream inoculation in the course of metal pouring; the in-mould inoculation, consisting in placing the fine-grain inoculant in the pouring basin or in the reaction chamber down the gating system; dosing the inoculant to the ladle in the form of cored wire [1][2][3][4][5][6][7]. One of a variety of such methods, which is particularly worth attention, is the pneumatic dosage of inoculant to the molten metal by the inoculant/carrier gas two-phase stream [1,2,8].…”