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1
Content available The Influence of Graphite Type on the Abrasive Wear of AlMg10 Matrix Composites
Łągiewka M., Konopka Z., Zyska A., Nadolski M.
Archives of Foundry Engineering
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2015
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Vol. 15, iss. 1 spec.
65--68
EN
The presented work discuss the influence of various types of graphite additions on the abrasive wear of AlMg10 matrix alloy composites. Flake graphite, electrographite, and short graphite fibre were used as a composite reinforcement. Composites containing 10 vol. % of graphite particles were produced by mechanical mixing of the liquid alloy with simultaneous introduction of the reinforcement. Composite suspensions were gravity cast into metal moulds. The achieved castings were tested for the abrasive wear. Also the pure matrix alloy was examined. Microphotographs of the produced materials were taken, the specimens were also examined after the abrasion test by observing the microsections perpendicular to the abraded surface. The carried out experiments allow to state that even the little addition of graphite influences beneficially the tribological properties of composite under small loads applied to the frictional pair. It was found that under the increased load (30 N) the least abrasive wear is exhibited by the composite reinforced with graphite fibre, the largest one occurring for the composite reinforced with electrographite. The composite reinforced with electrographite, however, exhibited the mass loss less by 25% than the pure matrix alloy.
2
Content available remote Influence of the microstructure and loads on tribological properties of G155CrNiMo4-3-3 cast steel
Krawczyk J.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 3
39--44
EN
Materials for mill rolls, fulfilling high requirements due to difficult exploitation conditions, are cast steels of adamite grade. Those are cast steels of pearlitic matrix with uniformly distributed cementite precipitations (e.g. hypereutectoid). In respect of a microstructure and a chemical composition these steels are hypereutectoid steels. They contain chromium (app. 1 %) and nickel (app. 0.5 %) and sometimes have an increased content of silica. Admissible is also a content of Mo (app. 0.4 %). An uniformly distributed carbide phase can be obtained by the proper heat treatment. The determination of the heat treatment influence on tribological properties - in dependence of the applied load - of adamite hypereutectoid G155CrNiMo4-3-3 cast steel, used for mill rolls - was the aim of the hereby paper. The purpose of the applied heat treatment was to change the hypereutectoid cementite morphology. Tribological tests were carried out at a room temperature by means of the T-05 tester, at loads of: 50, 100 and 150 N. Bearing steel 100Cr6 of a hardness 57 HRC was used as a counter sample. Testing time was 400 seconds. During the test the abrasion products were being removed from the counter sample. The performed investigations allow to draw conclusions regarding the influence of the hypereutectoid cementite morphology and loads on a wear mechanism and intensity of wearing of hypereutectoid adamite cast steel.
3
Content available remote Influence of a matrix on properties of mottled cast iron applied for mill rolls
Krawczyk J., Pacyna J.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 3
45--50
EN
Mill rolls are ones of the most expensive tools applied in plastic working processes and have to satisfy several criteria, which allow them to be used. Cast iron mill rolls, due to their fracture toughness and tribological properties, are the most often applied at hot-rolling in the last rolling stands. This results from the smallest dynamic loads of such rolling stands and the decisive influence of the surface quality of these tools on the surface quality of the rolled product. An improper microstructure of rolls can lead to their premature wearing, e.g. broken flanges, pivots twisting off etc. By means of the heat treatment the matrix microstructure and morphology of carbide precipitations can be modified and this in-turn can influence cast iron properties. Determination of the influence of microstructure changes, caused by the heat treatment, on the properties of EN-GJN-HV300 low-alloy cast iron, after its modification and spheroidization – is the aim of the present paper. Those changes are based on the formation pearlitic or bainitic matrices at the similar morphology of graphite and ledeburitic cementite precipitations. The performed investigations should enable designing the heat treatment of cast iron metallurgical rolls in such a way as to obtain the optimal microstructures for functional parameters of these type of tools. The influence of changing the pearlitic matrix into the bainitic one on such properties as: hardness, impact strength, tensile strength, creep limit, bending strength and a stress intensity factor KIc was investigated in this study. Samples for testing, the listed above mechanical properties, were taken from an industrial casting with care to have pieces of very similar crystallization conditions.
4
Content available remote Characteristic of intermetallic phases in cast dental CoCrMo alloy
Podrez-Radziszewska M, Haimann K., Dudziński W, Morawska-Sołtysik M.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 3
51--56
EN
Apart from chromium and molybdenum, casting alloys of cobalt usually contain also up to 0.35 % of carbon. With significant content of carbon, presence of carbide-forming alloying elements results in creating carbide phases. These alloys are characterised by dendritic structure of solid solution of chromium and molybdenum in cobalt with interdendritically precipitated carbides. Because of high chromium content, dominating are M23C6-type carbides, but chromium-rich carbides can be also of M7C3 and M3C2-types. The other elements in the alloy result in creating M6C and MC-type carbides. In the case of low carbon content, creating carbides and forming intermetallic phases based on the alloying elements and cobalt become limited. The presented research was aimed at characterising structure of the cobalt-based dental alloy containing trace quantity of carbon. Characterised were intermetallic phases hardening the alloy. Microscopic examinations using light microscopy, SEM and TEM were carried out. Chemical microanalysis of the precipitates using X-ray analyser EDS was performed, as well as phase analysis using selected area electron diffraction.
5
Content available remote Wear resistance of cast iron
Pietrowski S., Gumienny G.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 3
173-180
EN
In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron - the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.
6
Content available remote Structural and strength characteristics of wear-resistant martensitic steels
Dudziński W., Konat Ł., Pękalski G.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 2
21-26
EN
The paper presents structural, strength and impact resistance characteristics of a construction materials group. These are low-alloy steels of martensitic type structure, showing very high strength moduli, high wear resistance in the dynamic load conditions, and good weldability. Subject of the studies has been the most commonly used group of Hardox steels (Hardox 400 and Hardox 500), as well as the Polish equivalents of those materials (HTK 700 and HTK 900). It has been shown that despite similarity of chemical composition and production processes, the steels differ somewhat in structure, which influences their strength and usability (an operating experiment has been performed). Unfavourable structural changes in welded joints deteriorate their operating properties in the heat-affected zones, and cause clear drop in the wear resistance, despite the application of welding procedures recommended by a producer. The work presents synthesis of knowledge on that modern and still not well recognized group of steels, documented with results of own studies.
7
Content available remote Choice of material and development of technology to manufacture the working parts of a rotor operating in machine for turning of triangular heaps
Uhl W., Pirowski Z., Czekaj E., Wodnicki J.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 2
188-192
EN
The theoretical part of the study discloses the genesis of the research which originated from a possibility of replacing the so far used expensive machine parts with parts cheaper and yet offering similar quality and performance life. A short characteristic of the machine was given where the main operating parts made so far from steel were replaced with parts made from cast iron. The equipment and its main applications were described. In the research part of the study several types of alloys were proposed. Their use is expected to ensure the required performance life of parts combined with price reduction. A short characteristic of the proposed material was given. A technology of making moulds for the said machine parts was developed. Using this technology, the respective moulds were made and poured next with three cast alloys. One of the proposed materials was subjected to four types of the heat treatment, two alloys used as reference materials were left in as-cast state. The castings were fettled and weighed. The hardness of the cast materials was measured. The working (turning) parts were delivered for operation to a sewage-treatment plant where, after assembly in a turning machine, the performance tests were conducted.
8
Content available remote Enrichment of casting surface in founding process
Szajnar J., Wróbel P., Wróbel T.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 3
153-156
EN
A lot of cast steel and cast iron properties, also usable, depend on physical and chemical properties of surface layer, such as: hardness, corrosion resistance, abrasive wear resistance. The paper presents directly method of surface enrichment on casting in founding process. Layer in form of high-speed steel HS 18–0–1 plate was placed on G25CrSiMnMoNi 4–4–4–2,5–4 cast steel hammer of crusher. To investigations it was used light microscopy and scanning electron microscope. Microanalysis of chemical microanalysis of chemical composition and hardness measurements of transient zone between cast steel and steel were made. Analysis of research result show that, exists possibility of increase in hardness and abrasive wear resistance by put on casting surface a tool steel or sintered carbides plates, which are from scrap after waste of turning tool or face milling cutter. Moreover, applied activated alloy is very useful in this method of casting surface enrichment directly in founding process.
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