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1
Content available Effect of Cr, Mo and Al on Structure and Selected Mechanical Properties of Austenitic Cast Iron
Medyński D., Janus A.
Archives of Foundry Engineering
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2019
|
iss. 4
39--44
EN
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.
2
Content available Influence of Heat Treatments and Ni Content on Properties of Martensitic Stainless Steel
Čamek L., Kaňa V., Záděra A., Myška M.
Archives of Foundry Engineering
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2018
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Vol. 18, iss. 2
220--225
EN
The article deals with the influence of chemical composition of martensitic stainless steel for castings GXCrNi13-4 (the 1.4317 material) on mechanical properties and structure of as cast steel after heat treatment. Properties of these martensitic stainless steel are heavily influenced by chemical composition and structure of the material after heat treatment. Structure of these steels after quenching is formed with martensite and residual austenite. When tempering the steel the carbon content in martensite is reduced and gently deposited carbides occur. The way of heat treatment has a major impact on structure of martensitic steels with low carbon content and thus on strength, hardness and elongation to fracture of these steels. Chemical composition of the melt has been treated to the desired composition of the lower, middle and upper bounds of the nickel content in the steel within the limits allowed by the standard. Test blocks were gradually cast from the melt. The influence of the nickel equivalent value on structure and properties of the 1.4317 steel was determined from results of mechanical tests.
3
Content available Dilatometric Research of High-quality Nodular Cast Iron
Medyński D., Janus A.
Archives of Foundry Engineering
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2018
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Vol. 18, iss. 2
163--168
EN
In the research, relationships between matrix structure and hardness of high-quality Ni-Mn-Cu cast iron containing nodular graphite and nickel equivalent value were determined. Nickel equivalent values were dependent on chemical composition and differences between them resulted mostly from nickel concentration in individual alloys. Chemical compositions of the alloys were selected to obtain, in raw condition, austenitic and austenitic-martensitic cast iron. Next, stability of matrix of raw castings was determined by dilatometric tests. The results made it possible to determine influence of nickel equivalent on martensite transformation start and finish temperatures.
4
Content available Abrasive-wear Resistance of Austenitic Cast Iron
Medyński D., Janus A.
Archives of Foundry Engineering
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2018
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Vol. 18, iss. 3
43--48
EN
A research of wear resistance of an austenitic cast iron with higher resistance to abrasive-wear and maintained corrosion resistance characteristic for Ni-Resist cast iron is presented. For the examination, structure of raw castings was first formed by proper selection of chemical composition (to make machining possible). Next, a heat treatment was applied (annealing at 550 °C for 4 hours followed by air cooling) in order to increase abrasive-wear resistance. One of the factors deciding intensity of wear appeared to be the chilling degree of castings. However, with respect to unfavourable influence of chilling on machining properties, an important factor increasing abrasive-wear resistance is transformation of austenite to acicular ferrite as a result of annealing non-chilled castings. Heat treatment of non-chilled austenitic cast iron (EquNi > 16%) resulted in much higher abrasive-wear resistance in comparison to the alloy having pearlitic matrix at ambient temperature (EquNi 5.4÷6.8%).
5
Content available Effect of Chemical Composition on Structure and Corrosion Resistance of Ni-Mn-Cu Cast Iron
Medyński D., Janus A.
Archives of Foundry Engineering
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2016
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Vol. 16, iss. 3
59--62
EN
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 resistance to a much smaller extent than the nickel equivalent value, in particular concentration of elements with high electrochemical potential.
6
Content available Effect of Nickel Equivalent on Structure and Corrosion Resistance of Nodular Cast Iron Ni-Mn-Cu
Medyński D., Janus A.
Archives of Foundry Engineering
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2015
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Vol. 15, iss. 1 spec.
69--74
EN
Within the research determined was the effect of nickel equivalent on structure, hardness and corrosion resistance of nodular cast iron Ni- Mn-Cu. The examinations revealed a drop of thermodynamic stability of austenite along with decreasing nickel content. Along with in-creasing degree of austenite transformation, the created martensite resulted in significant increase of hardness (and of abrasion resistance as well) of the examined of cast iron, accompanied by insignificant decrease of corrosion resistance.
7
Content available Effect of nickel equivalent on austenite transition ratio in Ni-Mn-Cu cast iron
Janus A., Kurzawa A.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 2
53--58
EN
Determined was quantitative effect of nickel equivalent value on austenite decomposition degree during cooling-down castings of Ni-Mn- Cu cast iron. Chemical composition of the alloy was 1.8 to 5.0 % C, 1.3 to 3.0 % Si, 3.1 to 7.7 % Ni, 0.4 to 6.3 % Mn, 0.1 to 4.9 % Cu, 0.14 to 0.16 % P and 0.03 to 0.04 % S. Analysed were castings with representative wall thickness 10, 15 and 20 mm. Scope of the examination comprised chemical analysis (including WDS), microscopic observations (optical and scanning microscopy, image ana-lyser), as well as Brinell hardness and HV microhardness measurements of structural components.
8
Content available remote Wpływ wartości ekwiwalentu niklowego na strukturę żeliwa Ni-Mn-Cu
Janus A.
Archiwum Odlewnictwa
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2006
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R. 6, nr 18/2
159--164
PL
Na podstawie analizy struktur opracowano równanie ekwiwalentu niklowego dla odlewów wykonanych z żeliwa Ni-Mn-Cu zawierającego: 2,5-4,5% C; 1,5-3,0% Si; 2,0-8,0% Ni; 2,0-8,0% Mn i 0,1-5,0% Cu. Określono minimalną wartość ekwiwalentu, konieczną do uzyskania trwałej w temperaturze otoczenia austenitycznej struktury osnowy metalowej żeliwa w stanie po odlaniu.
EN
On the base of structures analysis the equation of nickel equivalent for castings made of Ni-Mn-Cr cast iron containing 2.5-4.5% C, 1.5-3.0% Si, 2.0-8.0% Ni, 2.0-8.0% Mn and 0.1-5.0% Cu was elaborated. The minimum value of this equivalent necessary for the obtainment of the stable austenitic structure of the rough castings at the ambient temperature was determined.
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