Artykuły (CN-mafe)

Permanent URI for this collectionhttps://repo.agh.edu.pl/handle/AGH/102851

Artykuły czasopisma Metallurgy and Foundry Engineering

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Access status: Open Access ,
Solidification conditions of gray and white cast iron. Part I, Theoretical background
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
The present work is based on a heat balance during the solidification of cast iron. Accordingly. an analytical expression was derived to relate the chilling tendency (CT) of cast iron with nucleation and growth processes associated with eutectic graphite and cementite constituents. A relationship is found between the CT and factors such as the physical-chemical state of liąuid, the distribution of nucleation sites, and the density of nucleation sites for eutectic grains. In particular, it is found that the casting modulus (M), enabling determinations of minimum wali thickness for chilled castings or chill widths in wedge shaped castings can be related to the CT. Finally, the present work provides a rationa-lization for the effect of technological factors such as the chemistry of the melt, inoculation practice. holding temperaturę and time on the resultant CT and chill of the cast iron.
Access status: Open Access ,
Eutectic transformation in ductile cast iron. Part 2 - Experimental verification
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In this work the predictions of a proposed analytical theory aimed at elucidating factors influencing on the nodule counts, the chill and the chilling tendency of nodular cast iron were experimentally verified. The experimental work was focussed on processing nodular cast iron under various inoculation conditions in order to achieve various physicochemical states of the experimental melts. In addition, plates of various wall thicknesses were cast and the resultant chilling tendency was established. Metallographic evaluations were made to determine the exhibited nodule counts in the experimental plates. Moreover, thermal analysis of these nodular cast irons was used to find out the degree of maximum undercooling for the graphite eutectic deltaTm. Finally, calculations were made using previously derived analytical expressions to determine graphite nodule counts, chilling tendency and critical wall thicknesses, below which the chill appears. From this analysis, it was found that there is good agreement between the theoretical predictions and the experimental outcome.
Access status: Open Access ,
Solidification conditions of gray and white cast iron. Part II, Experimental verification
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In this work, an experimental verification of the theoretical principles for the transition from gray to mottled and white cast iron solidification is presented. Experimental tests have been implemen-ted using plate and wedge shaped castings of various sizes. The experiments included inoculated and non-inoculated cast irons of different chemical compositions and time after the inoculation treatment. In addition, thermal analysis tests were employed to determine the degree of undercooling of graphite eutectic ATm. This included microstructural evaluations in order to establish the density of eutectic grain (cells). This procedurę enabled the calculation of the theoretical grain density (celi count) TV, the wedge value w, as well as the chilling tendency CT of cast iron. It was found that the predictions of the theoretical analysis are in good agreement with the experimental outcome for the chill exhibited in wedge and plate shaped castings.
Access status: Open Access ,
Determination of the surface tension for binary ionic solutions by means of Butler model
(2005) Iwanciw, Jerzy; Kalicka, Zofia Bronisława; Kawecka-Cebula, Elżbieta; Pytel, Krzysztof
It was attempted in this work to study the applicability of Butler approach to the metal oxide solutions. First of all, the authors tried to determine the impact of the thermodynamic activity coeffi-cients of the components of the bulk phase on the surface tension. The activity coefficients series expansions reported by Ban-ya and one of the authors of this work were used. The model eąuations were solved by means of a Newton regression method, which allowed to calculate the components contents in the surface phase. Those contents were subseąuently substituted into the modified Butler master eąuation, which gave desired finał surface tensions estimates for the considered oxide binaries. The computations were done for liquidMnO-SiO2 system (at 1843 K and 1990 K) and subseąuently for MnO-Al2O3 (at 2058 K) and MnO-CaO (at 2473 K) systems. For MnO-SiO2 system at 1843 K, theobtained results could be compared to the experimental ones and a fairly good agreement was found. For MnO-Al2O3 and MnO-CaO systems, unfortunately, there is no experimentally measured surface tension data, therefore it was not possible to make any comparison. Nevertheless, the model may be ąuite useful for the surface tension estimates for the systems, which have not been yet investigated and such model calculations like presented in this work may provide acceptable predictions.
Access status: Open Access ,
Design of manufacturing of welding neck type rings
(2005) Malinowski, Zbigniew; Madej, Wiesław; Musiał, Andrzej; Hajduk, Zbigniew; Wolski, Aleksander
Computer aided design of the rolling process for welding neck 20' and 24' type rings on the Thyssen-Wagner 125-100 mill is described in the paper. Numerical simulations of processes of preform shaping and ring rolling were performed using ring-roll finite element software. The optimal shape of the preform and rolling curve were selected on the basis of results of simulations, as well as on the basis of experimental data. Values of stresses, strains, strain rates and temperatures during rolling were determined and resutts were validated by comparison with the data monitored during the real industrial process. Obtained results were used for the design of tools for forging and rolling of welding neck type rings.
Access status: Open Access ,
Determining optimum volume of cold and hot blast air in single-row coke cupolas
(2005) Khatemi, Belkheir; Longa, Władysław
In this study a formuła was derived to calculate optimum volume of cupola blast air [m /(m -s). standard operating conditions], cold or hot, for single-row coke cupolas, assuming that the lower boun-dary of the melting zone is adhacent to the upper boundary of the combustion zone (the condition of optimum cupola running formulated by A. Achenbach in 1931). Relevant eąuations and tables have also been developed to make the calculations easier. From computations madę in this study it follows that the optimum blast air volume is increasing with an increase of the blast air temperaturę, assuming for cold blast a value close to 100 m /(m -min) (Buzek postulate), with modulus of the metallic charge lumps changing in a rangę of 15 to 20 mm.
Access status: Open Access ,
Modeling of near-net forging of thin-walled parts of strain rate sensitive alloy
(2005) Bednarek, Sylwia; Sińczak, Jan; Skubisz, Piotr
Numerical modelling of a single-operation forging process of a radial bladed impeller forging as one piece is presented. The analysis have been performed using high-melting-alloy model material. A several alternative technologies differing in temperature and forming speed. Evaluation of the correctness of a forging process were based on distribution of effective strain, effective strain rate, mean stress as well as fllling of the cavities of a die-impression in thin-walled ribs type areas.
Access status: Open Access ,
Oxygen-blowing remelts of low-alloyed Cr-Mn-Ni-Mo steels with the variable oxidation rate of carbon, chromium and phosphorus
(2005) Sobula, Sebastian; Głownia, Jan
Low-alloy Cr-Mn-Ni-Mo cast steels and high-alloy manganese cast steels are freąuently use as castings in such areas as minerał industry and power industry. Melting technology of these steels is often based on the use the return-scrap in charge, because the prices of nickel and molybdenum are very high. Basic electric arc furnaces were used in the oxidation re-melting of high manganese and Iow alloyed Cr-Mn-Ni-Mo steel scraps. The measuring of bath temperaturę and chemical composition were realized for control of C, P and Cr oxidation rates. This article shows effect of two methods of carbon boil, used in re-melting technology: first is carbon oxydation by iron ore and second is oxygen-blo-wing. The results of these measurements showed that at the oxygen blowing under the pressure of ca 0,6-K),8 MPa and oxygen capacity of 0,37-^0,60 N-m /(min-Mg), the average value of decarburisation ratę is 1,03-^2,08% C/h, according the temperaturę of the bath. In the same condition of oxidation, the dephosphorisation ratę in Cr-Mn-Ni-Mo is 0-K),12% P/h. It was shown that the temperatures above 1620°C protected steel bath against high chromium losses. At these temperatures the average value of phosphor oxidation ratę is 0,070% P/hour.
Access status: Open Access ,
An effect of aromatic diluent addition on the selected properties of epoxy resin
(2005) Hutera, Barbara; Drożyński, Dariusz
The article describes the studies which have been conducted on the dynamic wetting of quartz grains by EPIDIAN 5 resin and by this resin with an addition of 5 wt. %, 20 wt. % and 30 wt. % of xylene at different temperatures. In the case of the investigated resin, the wetting process dynamics is best described by a logarithmic function: theta = A Int + B0, where: theta is the contact angle after time t, and A and B0 are constants characteristic of this process at a given temperature. It has been proved that with 5 wt. % addition of xylene both constants assume a value different than zero. With addition of 20 wt. % and 30 wt. % of xylene, the State of equilibrium is reached almost immediately, and it is expressed by a zero value of constant A. The infrared spectroscopy did not reveal the presence of any chemical reactions between the EPIDIAN 5 resin and xylene, thus confirming that the chemical structure of xylene molecule affects the type of interaction and proves the non-active behaviour of xylene as a diluent. The importance of the studies for foundry sand practice has been stressed.
Access status: Open Access ,
The theoretical background for calculation of geometrical parameters of the stable melting zone in single-row coke cupolas
(2005) Longa, Władysław; Khatemi, Belkheir
In the present work, the stable melting zone was divided into sequences (systems) of the melting pieces of metal, to derive next some equations used in calculation of the mean volume and surface area of the pieces in individual sequences (for plates of any arbitrary value of their relative dimensions). The analysis of the obtained relationships has proved that in calculation of the geometrical parameters of the melting zone (zone height, mass of melting metal, surface of development, number of the melting pieces of metal) it is possible to use the term of a mean integral volume and mean integral surface area of the pieces of metal in a zone.
Access status: Open Access ,
Universal method of calculation of radiation recuperators with microfinned surface
(2005) Karczewski, Krzysztof
Universal method of calculation of radiation recuperators with microfinned surface were elaborated. The algorithm of method applied: model investigations of heat transfer and hydraulic resistance on recuperator elements with microfins, the surface ratio and micro-fin efficiency. The universal method of calculation developed in the paper makes possible the recuperator's design to industrial furnace.
Access status: Open Access ,
Eutectic transformation in ductile cast iron. Part I - Theoretical background
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In the present paper, heat balance is incorporated in developing expressions for the solidiflcation kinetics of divorced eutectic in ductile cast iron taking into account nucleation and growth processes for spheroidal graphite. Accordingly, a new analytical equations were derived that describe the nodule count N and the chill and chilling tendency CT of ductile cast iron. From this analysis, it is viable to predict cast nodule counts as well as the chill and CT for ductile iron from experimental data on cooling rates, chemical composition and other factors. Finally, the effect of technological factors on the resultant nodule counts the chill and chilling tendency is considered in this work.
Access status: Open Access ,
Graphite particle size distribution in nodular cast iron
(2005) Wiencek, Kurt; Skowronek, Tadeusz; Khatemi, Belkheir
A system of non-overlapping random spheres, whose diameters have the Weibull distribution may be used as a model for the graphite in nodule cast iron. For a given material the model probability density function of the Weibull distribution may be determined (as the first approximation) by fitting the PDF of model profile diameters to the one of graphite particle sections. The Weibull distribution may be used as the basis for quantitative metallography of the graphite phase in nodular cast iron.
Access status: Open Access ,
Modelling of microstructure development in forging of a windmill shaft
(2006) Sińczak, Jan; Skubisz, Piotr; Łukaszek-Sołek, Aneta; Pietrzyk, Maciej
The paper presents the results of investigation of microstructure evolution in hot-deformed steel in the process of forging of large forgings. Using a forging of a windmill main shaft as an example, description of the technological process is presented, focused on phenomena occurring in the microstructure during hot-forging. Investigation of the microstructure during and after forging of a shaft was made. The results of theoretical calculation of microstructure evolution during subsequent stages of production cycle are based on temperature changes plots derived from industrial practice. Simulation of microstructure evolution allowed plotting changes of grain size and recrystallized volume fractions versus time during forging and reheating operations.
Access status: Open Access ,
Thermal degradation of waste polyolefines and their application in blast-furnace process
(2006) Kuźnia, Monika; Magdziarz, Aneta
Nowadays about 60% of world production and consumption of plastics are polyolefines. They are used as packaging, in building engineering, automotive industry or electronic engineering. High calorific value and proper Chemical composition of polyolefines (based on carbon and hydrogen) make them ideal for use in a wide range of applications. The polyolefines can be used as a substitute for coke in blast-furnace processes. This paper outlines thermal decomposition of PE-LD, PE-HD, PP which are used in agriculture and packaging from household. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were used as analytical methods.
Access status: Open Access ,
Computer modelling of microstructure development during multistage deformation
(2006) Nowak, Jarosław; Rauch, Łukasz
The objective of this paper is implementation of microstructure development equations and their inclusion in commercial finite element code of Forge2 software. The created module is used for prediction of microstructure evolution in hot metal forming process. Calculations were carried out based on multistage forging process. Inclusion of the structural model into the Finite Element Method (FEM) source codes creates possibilities to take into account microstructural features already at the designing stage of the final industrial process.
Access status: Open Access ,
Effect of deformation degree on properties of forgings after thermomechanical treatment
(2006) Skubisz, Piotr; Sińczak, Jan; Bednarek, Sylwia; Łukaszek-Sołek, Aneta
Utilization of thermo-mechanical treatment in forging medium-carbon alloyed steel including microaddition of titanium is presented. Results of forging tests carried out in industrial conditions with a use of a high-speed forging press in conventional cooling conditions are compared with those involving controlled forging and direct cooling after forging. Significant grain refinement accompanied by increase in tensile properties was observed. It was also concluded that deformation degree has an effect on the final mechanical properties.
Access status: Open Access ,
High-efficiency ceramic recuperators to glass furnaces
(2006) Karczewski, Krzysztof
Mathematical model of high-efficiency ceramic recuperators using the new generation of shapes was elaborated. The parameters and characteristics magnesia, fusion cast alumina-mullite-zirconia, chamotte recuperator shapes were compared. Ceramic recuperator to glass tank was calculated by the model.
Access status: Open Access ,
Effect of grain refinement on mechanical properties of microalloyed steels
(2006) Muszka, Krzysztof; Majta, Janusz; Bienias, Łukasz
The goal of the present work was to study the effect of grain size and strain rate on the mechanical properties of microalloyed steels. The range of the microstructures was developed and their mechanical properties were measured under quasi-static conditions. The influence of different thermomechanical parameters on grain refinement, and thus, on final mechanical behavior of these steels seems to be very important issue, because of their application as the materials with both high strength and ductility. There is a clear lack of understanding of the role of intermediate ultrafine microstructures on the mechanical response of structural steels, which is important as this is the refinement level most likely to be achieved under industrial processes. The main scope of this research includes the development of thermomechanical treatments to produce ultra fine-grained steels with enhanced properties. These materials will be developed for the application in many industries (e.g. automotive industry, shipbuilding), and in any commercial applications where very good properties and good-quality construction materials are of paramount importance. The results of this work will allow to systematically correlate the evolution of deformation microstructure and the deformation mechanisms operating in fine-grained materials during processing. This work will also be directed towards understanding the specific strengthening mechanisms by which the plastic deformation leads to a refined grain size.
Access status: Open Access ,
To the memory of Professor Stanisław Słupek (1938-2006)
(2006) Nocoń, Jerzy; Telejko, Tadeusz