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EN
Unmodified AlSi20 alloy were casted at the research station, allowing for sequential multipoint cooling using a dedicated computer- controlled program. This method allows for the formation of the microstructure of hypereutectic AlSi20 alloy and also increases hardness. Primary silicon dendrites were found in the microstructure of cooled samples. Based on these dendrites, the formation of primary silicon particles is explained. Cooling of casting die with a water mist stream causes changes in solidification, which leads to expansion of the boundary layer with columnar crystals and shrinkage of the core zone with equiaxed crystals. It also causes more regular hardness distribution around pre-eutectic Si crystals, which can lead to tensile strength and machinability improvement.
EN
The paper presents an analysis of the effect of shape of primary silicon crystals on the sizes of stresses and deformations in a surface layer of A390.0 alloy by Finite Elements Method (FEM). Analysis of stereological characteristics of the studied alloy, performed based on a quantitative metallographic analysis in combination with a statistical analysis, was used for this purpose. The presented simulation tests showed not only the deposition depth of maximum stresses and strains, but also allowed for determining the aforementioned values depending on the shape of the silicon crystals. The studied material is intended for pistons of internal combustion engines, therefore the analysis of the surface layer corresponded to conditions during friction in a piston-cylinder system of an internal combustion engine having power of up to 100 kW. The obtained results showed important differences in the values of stresses and strains up to 15% between various shape of the silicon crystals. Crystals with sharp edges caused higher stresses and deformation locally than those with rounded shapes.
EN
In the paper the method of data modeling for damages, that has values higher than zero, is being shown. With the use of Weibull distribution, with prior regression and correlation analysis, the chosen parameters, that define durability and break down level of two populations of AlSi17Cu5Mg, were set. The calculation sheet that is shown for reliability allows the creation of so called survival chart, and on the basis of durability data the average warrantee time can be defined at the pre-exploitation stage.
EN
In the dissertation it has been shown, that so called „time-thermal treatment” (TTT) of the alloy in liquid state, as overheating the metal with around 250°C above the Tliq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, Rm, R0,2). It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform arrangement of the Si primeval crystals in the warp, and α(Al) solution type, supersaturated with alloying elements present in the base content (Cu, Mg) assures not only increased durability in the ambient temperature, but also at elevated temperature (250°C), what is an advantage, especially due to the use in car industry.
EN
The paper presents fatigue tests (unilateral pulsating vibrations) for hypereutectic silumin AlSi17Cu5Mg aimed at simulation of deflection of the piston head in a combustion engine. The methodology of the tests and the way of marking the deflection of the tested material is described together with the detailed description of the test stand. The fatigue resistance ZG was identified in the tested material and a Wöhler diagram was prepared to show the areas of limited and unlimited fatigue resistance.
EN
In the dissertation it has been shown, that so called “time-thermal treatment” (TTT) of the alloy in liquid state as overheating the metal with around 250°C above Tliq. and detailing it in temperature for 30 to 40 minutes has the influence on changing the crystallization parameters (Tliq., TEmin., TEmax., TE(Me), TSol.). It was ascertained, that overheating the AlSi17Cu5Mg alloy substantially above Tliq. results with microcrystalline structure. Evenly distributed in the eutectic warp primeval silicon crystals and supersaturated with alloying additives of base content (Cu, Mg, Fe) of α(Al) solution, ensures not only increase durability in ambient temperature, but also at elevated temperature (250°C), what due to it’s use in car industry is an advantage.
EN
The paper presents the results of studies on the effect of the AlSi17Cu5 alloy overheating to a temperature of 920°C and modification with phosphorus (CuP10) on the resulting mechanical (HB, Rm, R0.2) and plastic (A5 and Z) properties. It has been shown that, so-called, "time-thermal treatment" (TTT) of an alloy in the liquid state, consisting in overheating the metal to about 250°C above Tliq., holding at this temperature by 30 minutes improves the mechanical properties. It has also been found that overheating of alloy above Tliq. enhances the process of modification, resulting in the formation of fine-grain structure. The primary silicon crystals uniformly distributed in the eutectic and characteristics of the \alfa(Al) solution supersaturated with alloying elements present in the starting alloy composition (Cu, Fe) provide not only an increase of strength at ambient temperature but also at elevated temperature (250°C).
EN
Majority of combustion engines is produced (poured) from Al-Si alloys with low thermal expansion coefficient, so called piston silumins. Hypereutectic alloys normally contain coarse, primary angular Si particles together with eutectic Si phase. The structure and mechanical properties of these alloys are highly dependent upon cooling rate, composition, modification and heat-treatment operations. In the paper one depicts use of the ATND method (thermal-voltage-derivative analysis) and regression analysis to assessment of quality of the AlSi21CuNi alloy modified with Cu-P on stage of its preparation, in aspect of obtained mechanical properties (R0,02, Rm, A5, HB). Obtained dependencies enable prediction of mechanical properties of the investigated alloy in laboratory conditions, using values of characteristic points from curves of the ATND method.
PL
W pracy przedstawiono wyniki pomiaru geometrii nadtopień i parametrów strukturalnych warstwy wierzchniej odlewów ze stopu AK 20 uszlachetnionej szybką krystalizacją. Proces szybkiej krystalizacji realizowano z wykorzystaniem nadtapiania powierzchniowego odlewów plazmą łuku elektrycznego – metoda GTAW (Gas Tungsten Arc Welding). Stosowano natężenie prądu 100, 200 i 300 A oraz prędkość przemieszczania plazmy łuku elektrycznego 200, 400 i 800 mm/min. Określono związki pomiędzy parametrami technologicznymi procesu GTAW, a geometrią nadtopień i strukturą materiału z obszaru nadtopień.
EN
In this work the results of measurement of the fusion geometry parameters and structural parameters of AK 20 alloy after rapid solidification were described. The rapid solidification process was realized with the GTAW method (Gas Tungsten Arc Welding).The current intensity 100A, 200A and 300A as well as electric travel speed 200 mm/min, 400 mm/min and 800 mm/min were used. The relationships between GTAW process parameters and fusion geometry parameters as well as structural parameters were defined.
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