Determined were direction and intensity of influence of alloying additions on the number of eutectic graphite colonies in austenitic cast iron Ni-Mn-Cu. Chemical composition of the cast iron was 1.7 to 3.3% C, 1.4 to 3.1% Si, 2.8 to 9.9% Ni, 0.4 to 7.7% Mn, 0 to 4.6% Cu, 0.14 to 0.16% P and 0.03 to 0.04% S. Analysed were structures of mottled (20 castings) and grey (20 castings) cast iron. Obtained were regression equations determining influence intensity of individual components on the number of graphite colonies per 1 cm2 (LK). It was found that, in spite of high total content of alloying elements in the examined cast iron, the element that mainly decides the LK value is carbon, like in a plain cast iron.
In the magazine Unser Danzig published by ex-citizens of Gdańsk in the years of 1949–2008, one must pay attention not only to politically-engaged texts, but also to obituaries which present lives of the deceased and missing their lost fatherland. The aim of these obituaries is not only to inform about someone’s death, but also to acccept the regional origin of the deceased, which is presented by linguistic and paralinguistic means.
A review of Filip Taterka’s Polish translation of the preserved fragments of Manetho’s History of Egypt.
In the paper, a relationship between chemical composition of Ni-Mn-Cu cast iron and its structure, hardness and corrosion resistance is
determined. The examinations showed a decrease of thermodynamic stability of austenite together with decreasing nickel equivalent value,
in cast iron solidifying according to both the stable and the metastable systems. As a result of increasing degree of austenite
transformation, the created martensite caused a significant hardness increase, accompanied by small decline of corrosion resistance. It was
found at the same time that solidification way of the alloy and its matrix structure affect corrosion resista
Within the presented work, the effect of austenite transformation on abrasive wear as well as on rate and nature of corrosive destruction
of spheroidal Ni-Mn-Cu cast iron was determined. Cast iron contained: 3.1÷3.4 %C, 2.1÷2.3 %Si, 2.3÷3.3 %Mn, 2.3÷2.5 %Cu and
4.8÷9.3 %Ni. At a higher degree of austenite transformation in the alloys with nickel equivalent below 16.0%, abrasive wear resistance
was significantly higher. Examinations of the corrosion resistance were carried out with the use of gravimetric and potentiodynamic
method. It was shown that higher degree of austenite transformation results in significantly higher abrasive wear resistance and slightly
higher corrosion rate, as determined by the gravimetric method. However, results of potentiodynamic examinations showed creation
of a smaller number of deep pinholes, which is a favourable phenomenon from the viewpoint of corrosion resistance.
The paper presents influence of soaking parameters (temperature and time) on structure and mechanical properties of spheroidal graphite
nickel-manganese-copper cast iron, containing: 7.2% Ni, 2.6% Mn and 2.4% Cu. Raw castings showed austenitic structure and relatively
low hardness (150 HBW) guaranteeing their good machinability. Heat treatment consisted in soaking the castings within 400 to 600°C for
2 to 10 hours followed by air-cooling. In most cases, soaking caused changes in structure and, in consequence, an increase of hardness in
comparison to raw castings. The highest hardness and tensile strength was obtained after soaking at 550°C for 6 hours. At the same time,
decrease of the parameters related to plasticity of cast iron (elongation and impact strength) was observed. This resulted from the fact that,
in these conditions, the largest fraction of fine-acicular ferrite with relatively high hardness (490 HV0.1) was created in the matrix. At
lower temperatures and after shorter soaking times, hardness and tensile strength were lower because of smaller degree of austenite
transformation. At higher temperatures and after longer soaking times, fine-dispersive ferrite was produced. That resulted in slightly lower
material hardness.
In this paper, the effect of changes the parameters of heat treatment on the structure and the degree of elements segregation was
determined, in the context of corrosion resistance of ductile iron Ni-Mn-Cu, containing 7.2% Ni, 2.6% Mn and 2.4% Cu. In the condition
after casting, castings of austenitic matrix and 160HBW hardness were obtained. The achieved castings were soaked at 450, 550 and
650°C for 4, 8 and 12 hours, then cooled down at the ambient air. In most cases, the heat treatment resulted in a change in the castings
matrix, had the consequence of increasing their hardness in comparison to raw castings. Increasing the temperature and prolonging soaking
time resulted in increasing the degree of transformation of austenite, while reducing the degree of elements segregation. This led to the
formation of slightly bigger number of pitting due to corrosion, but not so deep and more evenly distributed in comparison to raw castings.
Wherein the results of corrosion tests show that heat treatment of castings did not significantly change their corrosion resistance in
comparison to raw castings, in contrast to the significant increase in mechanical properties.
Within the presented research, effect of annealing on nature of corrosion damages of medium-nickel austenitic nodular cast iron castings,
containing 5.5% to 10.3% Ni, was determined. Concentration of nickel, lower than in the Ni-Resist cast iron, was compensated with
additions of other austenite-stabilising elements (manganese and copper). In consequence, raw castings with austenitic matrix structure and
gravimetrically measured corrosion resistance increasing along with nickel equivalent value EquNi were obtained. Annealing of raw
castings, aimed at obtaining nearly equilibrium structures, led to partial austenite-to-martensite transformation in the alloys with EquNi
value of ca. 16%. However, corrosion resistance of the annealed alloys did not decrease in comparison to raw castings. Annealing of
castings with EquNi value above 18% did not cause any structural changes, but resulted in higher corrosion resistance demonstrated by
smaller depth of corrosion pits.
Results of a research on influence of chromium, molybdenum and aluminium on structure and selected mechanical properties of Ni-Mn-Cu cast iron in the as-cast and heat-treated conditions are presented. All raw castings showed austenitic matrix with relatively low hardness, making the material machinable. Additions of chromium and molybdenum resulted in higher inclination to hard spots. However, a small addition of aluminium slightly limited this tendency. Heat treatment consisting in soaking the castings at 500 °C for 4 h resulted in partial transformation of austenite to acicular, carbon-supersaturated ferrite, similar to the bainitic ferrite. A degree of this transformation depended not only on the nickel equivalent value (its lower value resulted in higher transformation degree), but also on concentrations of Cr and Mo (transformation degree increased with increasing total concentration of both elements). The castings with the highest hard spots degree showed the highest hardness, while hardness increase, caused by heat treatment, was the largest in the castings with the highest austenite transformation degree. Addition of Cr and Mo resulted in lower thermodynamic stability of austenite, so it appeared a favourable solution. For this reason, the castings containing the highest total amount of Cr and Mo with an addition of 0.4% Al (to reduce hard spots tendency) showed the highest tensile strength.
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