|Marek Kranc, Andrzej Gwiżdż, Krzysztof Jaśkowiec
The results of technological tests (chemical composition, solidification curves, microstructure) of ductile cast iron smelting in the Foundry Research Institute in an induction furnace. In the case of crystallization of spheroidal graphite no long fixed temperature stop associated with the crystallization of the structure was observed, and then rapid reduction of the temperature at the end of solidification process, with a clearly visible thermal inflection point during eutectic and graphite crystallization. The temperature, after reaching the maximum, slowly but steadily declined, and the inflection point of the end of the crystallization was difficult to determine. In the case when graphite precipitated in the vermicular form the image of the cooling curve was of indirect nature. In fact there was a stop with fixed temperature but it was shorter than in the case of scale graphite occurrence and there was no clear inflection point observed after the end of solidification. Suspending the molten metal in the induction furnace during the test resulted in a significant loss of magnesium assimilated in the process of spheroidization. The research was carried out on behalf of Fabryka Armatur JAFAR SA under the Innovative Economy Operational Programme 2007-2013, project: "Implementation of innovative technology of valve manufacturing in Fabryka Armatur JAFAR SA".
Keywords: ductile cast iron, cast iron fittings, structure,
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The study was conducted to determine the effect of spheroidization and modification method, of the CE value, the content of magnesium and lanthanum on susceptibility to form shrinkage defects, structure and resistance properties of ductile cast iron on thin-walled castings. It was stated that cast iron in the range 4-25 mm is sensitive to wall thickness, especially at very low concentrations of magnesium. It turned out that the most effective modifier was the alloy with barium content. There was no significant effect of lanthanum on the properties of cast iron introduced in spheroidizing mortar as well as in the modifier.
Keywords: cast iron, spheroidization, modification, structure, resilience,
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Andrzej Gwiżdż, Marcin Małysza, Mieczysław Nowak
A simulation analysis was carried out on the casting and solidification of EN-GJS-400-15 spheroidal iron for production of soft-sealed wedge gates for PE pipe gas networks. The analysis was made in the Flow-3D software. Based on the engineering documentation provided by Fabryka Armatur JAFAR SA spatial bodies were developed and analysed by simulation of the casting and solidification processes of wedge gates in three sizes: DN50, DN100 and DN150. Part I of the work  presents the simulation analysis for the DN150 gate; this section of the work, i.e. Part II, the simulation applies to the DN50 gate.
Keywords: computer assisted casting production, casting and solidification simulation, cast iron fittings for gas transmission systems,
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Marcin Małysza, Mieczysław Kuder, Mieczysław Nowak
Modernisation works aiming at lowering the weight and
increasing performance of the range of ball reflux valves include also, among other things, lowering the weight (density) of floating balls being an important element of this type of valves. To define the possible benefits, a simulation research of the flow of clean water through a valve of nominal diameter DN125 mm was carried assuming two densities of the ball - used up to now ρ = 1,66 kg/dm3 and modernised ρ = 1,20 kg/dm3. The simulations aimed at determining the parameters defining the efficiency of the valves: rate of flow of the media and drops of pressure in 4 points of the valve, and the size and nature of this flow. A favourable effect of lowering the density of the ball on the working parametres of the valve, reduction of flow resistance and vibrations due to easier movement of the ball and less turbulent flow of the media was found. However, results directly proportional to the degree of reduction in the density of the ball should not be expected.
Keywords: reflux valve, flow, computer simulation,
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Mieczysław Kuder, Robert Żuczek
Decreasing the density of check valve dip balls by nearly 30% results in significant decrease in the wall thickness of the domes from which the balls are assembled. During the high pressure curing process a risk occurs of excessive deformation or even damage of the elements. The numerical analyses conducted for three selected sizes of the type series revealed that the hazard exists in the lowest size, where the maximum stresses are close to the yield point for the selected cast iron grade, i.e. EN-GJS-400-15. The way to achieve the desired goal is to use a cast iron with higher strength, and to secure high precision of dome casts and their connection (lock) in order to avoid local stress concentration, resulting in the notching effect.
Keywords: numerical simulation, stress, rubber curing, spheroidal iron, check valves, fittings,
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Jan Szajnar, Mirosław Cholewa, Tomasz Wróbel, Tomasz Szuter
In the present paper research results of microstructure and selected mechanical properties of composite on EN AC-AlSi11 alloy matrix with reinforcement in the form of particle of Cr-Fe-C alloy (composite ex situ) and carbonitrides Ti, Zr, V (composite in situ) are presented. Metallographic studies were performed with the use of light microscope and with scanning electron microscope with EDS. Within the studies of performance characteristics measurements of hardness, abrasive wear resistance, impact resistance, tensile strength, yield point and elongation in as cast state and after heat treatment i.e. precipitation hardening and annealing were taken. Moreover the manufacturing method of brake disc casting from the studied composite with intermetallic phases reinforcement is presented.
Keywords: composite, aluminum, silicon, carbides, nitrides, mechanical properties, brake disc,
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