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1
Content available remote Effect of overheating degree on the solidification parameters of AlSi17CuNiMg silumin
Piątkowski J.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 2
103--106
EN
Melting technology, especially the temperature of overheating and pouring above the liquidus point Tliq as well as the cooling rate, determine alloy macro - and microstructure, and hence also casting performance properties. These parameters affect the solidification process and the formation of shrinkage cavities and porosity. So, it is important to choose the best parameters of the melting and pouring process, since on these parameters the process of crystal nucleation and growth as well as shaping of the alloy primary structure will depend. Hence it follows that the time-temperature treatment of molten alloys, hypereutectic silumins included, will also affect the solidification process. Therefore it is fully justified to examine in extenso the effect of overheating degree on parameters of the hypereutectic silumin solidification (Tliq, TE, Tsol) and temperature of complex eutectic crystallisation (due to additions of Cu, Ni and Mg), the more that these effects have not been so far fully investigated and understood.
2
Content available remote Effect of overheating degree of molten alloy on material reliability and performance stability of AlSi17CuNiMg silumin castings
Piątkowski J., Szymszal J.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 4
173--176
EN
The article discusses the effect of overheating degree (above the casting temperature) on material reliability of AlSi17 silumin. The examined alloys was poured at temperatures, 760; 870 and 980oC, holding the melt for 40 minutes and casting from the temperature of 760oC. The assessment of the impact of the degree of overheating was to analysis the tensile strength. From the results of the static tensile test, the main estimators of the descriptive statistics, and coefficients of variation. Having determined the boundary value δO for Weibull distribution, the value of „m” modulus was computed along with other coefficients of material reliability, proposed formerly by the authors. Basing on the obtained results, a model of Weibull distribution function was developed for the tensile strength with respective graphic interpretation. The time-temperature parameters of the melting and casting technology have been chosen to determine the scatter of resultant parameter (Rm) in function of overheating degree. The time-temperature treatment of hypereutectic AlSi17CuNiMg silumin, through its effect on the cluster structure of molten alloy, is shaping the material reliability and performance stability of castings.
3
Content available remote Determination of melting and solidification enthalpy of hypereutectic silumins
Piątkowski J., Szymszal J.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 1
97-100
EN
The study was related with determination of the values of enthalpy of melting and solidification of hypereutectic AlSi18, AlSi21 and AlSi24 silumins modified with phosphorus in the form of Cu-P. The calorimetry, preceded by thermal analysis and derivative thermal analysis (TA and DTA, respectively) was carried out on a high-temperature scanning calorimeter, model MHTC-96, made by SETARAM, applying the method of direct determination of parameters of the high-temperature process, and in particular of the enthalpy of phase transformations. Modern control and measuring instruments coupled with PC computer provide a very precise tool for determination of these transformations. An additional advantage was development of appropriate software called "SETSOFT", owing to which it was possible to determine in an easy way the enthalpy of the investigated phase transformations. Moreover, an additional thermal effect, related most probably with pre-eutectic crystallization of primary silicon, was observed and confirmed by calorimetric examinations.
4
Content available remote Statistical assessment of the effect of chemical composition on mechanical properties of hypereutectic AlSi17CuNiMg silumin
Szymszal J., Piątkowski J., Kliś J.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 3
163-166
EN
The paper presents a statistical assessment of the effect of chemical composition on mechanical properties of hypereutectic AlSi17 silumin, which is expected to act as a counterpart of alloys used by automotive industry and aviation for casting of high-duty engine parts in West European countries and USA. The studies on the choice of chemical composition of silumins were preceded by analysis of the reference literature to state what effect some selected alloying elements and manufacturing technology may have on the mechanical properties (HB, R_m and A5) of these alloys. As alloying additives, Cu, Ni and Mg in proper combinations were used. The alloy after modification with phosphorus (CuF) was cast into a metal mould. Basing on the results obtained, it has been reported that the developed silumin of hypereutectic composition is characterised by properties similar to its Western counterparts.
5
Content available remote Determination of reliability index and Weibull modulus as a measure of hypereutectic silumins survival
Szymszal J., Piątkowski J., Przondziono J.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 3
237-240
EN
The first part of the study describes the methods used to determine Weibull modulus and the related reliability index of hypereutectic silumins containing about 17% Si, assigned for manufacture of high-duty castings to be used in automotive applications and aviation. The second part of the study discusses the importance of chemical composition, including the additions of 3% Cu, 1,5% Ni and 1,5% Mg, while in the third part attention was focussed on the effect of process history, including mould type (sand or metal) as well as the inoculation process and heat treatment (solutioning and ageing) applied to the cast AlSi17Cu3Mg1,5Ni1,5 alloy, on the run of Weibull distribution function and reliability index calculated for the tensile strength Rm of the investigated alloys.
6
Content available remote An assessment of the effect of process history on the structure and mechanical properties of hypereutectic silumins
Szymszal J., Piątkowski J., Gierek A.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 3
167-170
EN
An effect of process history of manufacturing the AlSi17Cu3Mg1.5Ni1,5 alloy on its tensile strenght R_m hardness HB, and elongation A_5 was investigated. The individual elements of process history of the alloy fabrication included: type mould (sand or metal mould), modification process, and type of heat treatment (solutioning and ageing). Basing on a multivariance MANOVA test, it was possible to determine not only the effect of the main parameters, like foundry mould type, modification and heat treatment, but also an interaction of these effects. Consequently it has been concluded that the tensile strenght R_m of the examined alloy is statistically most affected by the process of modification, followed by the type of the applied heat treatment, and the type of foundry mould (metal mould). The strongest interactive effect on the value of R_m had a combination of the process and heat treatment.
7
Nowy pogląd na oddziaływanie fosforu w procesie kształtowania struktury pierwotnej siluminów nadeutektycznych
Binczyk F., Piątkowski J.
Archiwum Nauki o Materiałach
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2000
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T. 21, nr 3-4
199-213
PL
Wyniki przedstawione w pracy są zapowiedzią opracowania nadeutektycznych siluminów z przeznaczeniem na tłoki silników spalinowych. Badania nad krystalizacją i oceną modyfikacji siluminu nadeutektycznego prowadzono nową metodą polegającą na jednoczesnej analizie krystalizacji czterech próbek, w tym jednej bazowej. Zachowanie jednakowych warunków początkowych umożliwia poprawną analizę procesów zachodzących podczas krystalizacji i po modyfikacji. Badania prowadzono dla siluminu AK17 rafinowanego preparatem Rafglin-3 i modyfikowanego 0,05% P z dodatkami stopowymi W, Mo i Ti. Przedstawiono nowy pogląd oddziaływania fosforu w procesie modyfikacji siluminów nadeutektycznych, który jest wynikiem lokalnego przechłodzenia w mikroobszarach, spowodowanego parowaniem i rozprężaniem pęcherzyków par fosforu.
EN
In this work the results of investigations concerning the hypereutectic silumins to be used as engine ports have been shown. The results of investigations of hypereutectic silumin crystallisation using a new method are presented. This methods based on the simultaneous analysis of crystallisation of four samples, one being the basic sample. It assures identical conditions and enables correct interpretation of phenomena during of crystallisation and modification process. Studies were conducted for hypereutectic. AK17 modified by phosphorus to the 0,05% and alloy additions W, Mo and Ti, earlier refined by Rafglin3. New idea on the interaction mechanism of phosphorus during modification of hypereutectic silumins has been shown. According to this hypothesis the influence of phosphorus is the result of local supercoding caused by evaporation and decompression of phosphorus steam.
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