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1

Structure of Precision Castings Made of the Inconel 713C Alloy

Łyczkowska K., Adamiec J.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

19--24

EN

Inconel 713C alloy belongs to the group of materials with high application potential in the aerospace industry. This nickel alloy has excellent features such as high strength, good surface stability, high creep and corrosion resistance. The paper presents the results of metallographic examinations of a base material and padding welds made by laser beam on the Inconel 713C alloy. The tests were made on precisely cast test plates imitating low - pressure turbine blades dedicated for the aerospace industry. Observations of the macro- and microstructure of the padding welds, heat-affected zone and base material indicate, that the Inconel 713C alloy should be classified as a hard-to-weld material. In the investigated joint, cracking of the material is disclosed mainly in the heat-affected zone and at the melted zone interface, where pad weld crystals formed on partially melted grains. The results show that phases rich with chromium and molybdenum were formed by high temperature during welding process, which was confirmed by EDS analysis of chemical composition.

2

Monitoring of Manufacture Stability of Large Turbine Blades Using Infrared Thermography (IRT) in Investment Casting Technology

Herman A., Vrátný O., Kubelková I.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

9--14

EN

With increasing technology development, an increasing emphasis is placed on the precision of products, but cannot be guaranteed without a stable production process. To ensure the stability of the production process, it is necessary to monitor it in detail, find its critical locations and eliminate or at least control it. With such a precise manufacturing method as investment casting, such a process is a must. This paper therefore deals with monitoring the production process of wax models of large turbine blades using infrared thermography. The aim was to evaluate the critical locations of this production and to propose recommendations for their elimination or, at the very least, significant mitigation of their impact on the final quality of the large turbine blade casting.

3

The Althoff-Radtke Test Adapted for High Chromium Cast Iron

Kopyciński D., Siekaniec D., Szczęsny A., Sokolnicki M., Nowak A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

61--64

EN

The paper presents results of the possibility of adapting the Althoff-Radtke test for High Chromium Cast Iron. The Althoff-Radtke test is a clump attempt used for steel. The Althoff-Radtke test has four different lengths of clamp which qualifies it as a test to quantitatively take into account different kinds of shrinkage ΔL. The length of the slot of the cracked corner and the length of each staple (50 - 350 mm) are the parameters tendency to cast cracks. Castings of white cast iron have a high tendency to hot cracking due to the large range of solidification temperatures, unfavorable kinetics parameters of shrinkage, and especially a lack of expansion before shrinkage. Shrinkage of high chromium white cast iron is similar to the shrinkage of cast steel, and is approximately 2%. Therefore it is important to test susceptibility to hot cracks. Research was carried out under industrial conditions. Four melts were performed, one of the initial chemical composition and the other three modified by different amounts of Fe-Ti, respectively, 0.25%, 0.5% and 0.75% Fe-Ti. The propensity for hot cracking was based on the observation of the dark surface in the corner of the sample. The study shows that the Althoff-Radtke test can be adapted to determine the tendency for hot cracking of high chromium cast iron. It should however be noted that the test results can not be compared with those for other alloys.

4

The Effect of Shell Thickness, Insulation and Casting Temperature on Defects Formation During Investment Casting of Ni-base Turbine Blades

Raza M., Irwin M., Fagerström B.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4

115--123

EN

Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner sections.

5

Porosity of Castings Produced by the Vacuum Assisted Pressure Die Casting Method

Zyska A., Konopka Z., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

125--130

EN

The paper presents the results of investigations concerning the influence of negative (relative) pressure in the die cavity of high pressure die casting machine on the porosity of castings made of AlSi9Cu3 alloy. Examinations were carried out for the VertaCast cold chamber vertical pressure die casting machine equipped with a vacuum system. Experiments were performed for three values of the applied gauge pressure: -0.3 bar, -0.5 bar, and -0.7 bar, at constant values of other technological parameters, selected during the formerly carried initial experiments. Porosity of castings was assessed on the basis of microstructure observation and the density measurements performed by the method of hydrostatic weighing. The performed investigation allowed to find out that – for the examined pressure range – the porosity of castings decreases linearly with an increase in the absolute value of negative pressure applied to the die cavity. The negative pressure value of -0.7 bar allows to produce castings exhibiting porosity value less than 1%. Large blowholes arisen probably by occlusion of gaseous phase during the injection of metal into the die cavity, were found in castings produced at the negative pressure value of -0.3 bar. These blowholes are placed mostly in regions of local thermal centres and often accompanied by the discontinuities in the form of interdendritic shrinkage micro-porosity. It was concluded that the high quality AlSi9Cu3 alloy castings able to work in elevated temperatures can be achieved for the absolute value of the negative pressure applied to the die cavity greater than 0.5 bar at the applied set of other parameters of pressure die casting machine work.

6

Optimization of Side Feeders Systems by Means of Simulation of Solidification

Perzyk M., Kozlowski J., Mazur M., Szymczewski K.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

69--74

EN

Simulation software can be used not only for checking the correctness of a particular design but also for finding rules which could be used in majority of future designs. In the present work the recommendations for optimal distance between a side feeder and a casting wall were formulated. The shrinkage problems with application of side feeders may arise from overheating of the moulding sand layer between casting wall and the feeder in case the neck is too short as well as formation of a hot spot at the junction of the neck and the casting. A large number of simulations using commercial software were carried out, in which the main independent variables were: the feeder’s neck length, type and geometry of the feeder, as well as geometry and material of the casting. It was found that the shrinkage defects do not appear for tubular castings, whereas for flat walled castings the neck length and the feeders’ geometry are important parameters to be set properly in order to avoid the shrinkage defects. The rules for optimal lengths were found using the Rough Sets Theory approach, separately for traditional and exothermic feeders.

7

Methodology of Comparative Validation of Selected Foundry Simulation Codes

Ignaszak Z., Popielarski P., Hajkowski J., Codina E.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4

37--44

EN

The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the simulation results of available systems which are proposed in given technology.

8

Expert System for Analysis of Casting Defects - ESVOD

Elbel T., Králová Y., Hampl J.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 1

17--20

EN

The powerful tool for defect analysis is an expert system. It is a computer programme based on the knowledge of experts for solving the quality of castings. We present the expert system developed in the VSB-Technical University of Ostrava called ‘ESWOD’. The ESWOD programme consists of three separate modules: identification, diagnosis /causes and prevention/ remedy. The identification of casting defects in the actual form of the system is based on their visual aspect.

9

The influence of casting defects on fatigue resistance of elektron 21 magnesium alloy

Pikos I., Kiełbus A., Adamiec J.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

103--106

EN

The Mg-RE alloys are attractive, constructional materials, especially for aircraft and automotive industry, thanks to combination of low density, good mechanical properties, also at elevated temperature, and good castability and machinability. Present paper contains results of fatigue resistance test carried out on Elektron 21 magnesium alloy, followed by microstructural and fractographical investigation of material after test. The as-cast material has been heat treated according to two different procedures. The fatigue resistance test has been conducted with 106 cycles of uniaxial, sine wave form stress between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during the test, have been investigated with scanning electron microscope. The microstructure of specimens has been investigated with light microscopy. Detrimental effect of casting defects, as inclusions and porosity, on fatigue resistance has been proved. Also the influence of heat treatment's parameters has been described.

10

Technologia wytapianych modeli w zastosowaniu dla stopów miedzi

Rzadkosz S., Kranc M., Garbacz-Klempka A., Kozana J., Piękoś M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 3 spec.

143--148

PL

Technologia wytapianych modeli należy do najstarszych technologii odlewniczych. Historycznie służyła do odlewania narzędzi, broni i ozdób. Model wykonany z wosku pszczelego oblepiano gliną suszono i wypalano. Otrzymywano odlewy o dużej gładkości powierzchni, dokładności i precyzji wykonania ornamentu. Metodą tą odlewano niewielkie kilkugramowe odlewy jak i wielkogabarytowe pomniki. Współcześnie ta technologia jest wykorzystywana w wielu ważnych gałęziach produkcji zarówno artystycznej, jak i przemysłowej. Szczególnie w przemyśle zbrojeniowym, lotniczym, motoryzacyjnym, energetycznym, budowlanym, a nawet kosmicznym. W pracy przedstawiono wyniki badań i eksperymentów, prowadzonych w zakresie technologii odlewnictwa miedzi i stopów miedzi z zastosowaniem metody wytapianych modeli, zarówno w aspekcie historycznym, jak i współczesnej praktyki przemysłowej. Przykładowo przedstawiono analizę wybranych elementów dawnych technologii, form i odlewów wytworzonych w epoce brązu oraz wyniki badań dotyczące aktualnie produkowanych odlewów dla branży energetycznej. Jakość odlewów została oceniona na podstawie przeprowadzonych badań z zakresu mikrostruktury, składu chemicznego, przewodności elektrycznej i zawartości tlenu.

EN

Investment casting technology belongs to the oldest casting techniques. Historically, it was used for casting tools, weapons and ornaments. A model, made from beeswax, was covered in loam, dried and fired. The casts obtained were characterised by high surface smoothness, accuracy and precision of its ornaments. This method was used for relatively small casts as well as for big monuments. Nowadays, this technology is used in many fields of manufacturing, both artistic and industrial, especially in ornaments, aviation, automotive, power, construction and even space industry. This work presents the results of research and experiments conducted in the field of casting technology of copper and copper alloys, applying the investment casting method, both in its historical aspect and modern industrial practice. An exemplary analysis was presented of the chosen elements of the old technologies, moulds and casts, as well as the results of casts made currently for the power industry. The casts quality was evaluated based on the research of their microstructure, chemical composition, electrical conductivity and oxygen content.

11

Techniki spawalnicze w odlewnictwie. Napawanie

Wojciechowski W., Kowalski J. S.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 1 spec.

87--90

PL

W artykule omówiono problemy związane z naprawami wad odlewniczych. Przeanalizowano możliwości naprawy odlewów metodami spawalniczymi. Opisano technologię naprawy przez napawanie wlewnic wykonanych z żeliwa szarego. Napawanie prowadzono ręcznie elektrodami otulonymi oraz w osłonie gazów metodą MAG. Oceniono mikrostrukturę stref napawanych naprawianych odlewów oraz wyniki pomiarów twardości i rozkład mikrotwardości.

EN

In this paper discusses issues related to the repair of large castings. Analyzed the possibility repair of castings of welding methods. Describes the technology of repair by welding of cast iron ingot molds. Welding with coated electrodes was carried out manually and gas shielded MAG. Rated zones padded structure and performance measurement and distribution of microhardness.

12

Numerical analysis of influence of the mold material on the distribution of shrinkage cavities

Dyja R.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 1

15--18

EN

Production of castings, like any other field of technology is aimed at providing high-quality product, free from defects. One of the main causes of defects in castings is the phenomenon of shrinkage of the casting. This phenomenon causes the formation of shrinkage cavities and porosity in the casting. The major preventive measure is supplementing a shortage of liquid metal. For supplement to be effective, it is necessary to use risers in proper shapes. Usually, the risers are selected on the basis of determination the place of formation of hot-spots in the castings. Although in these places the shrinkage defects are most likely to occur, shape and size of these defects are also affected by other factors. The article describes the original program setting out the shape and location of possible cavities in the casting. In the program is also taken into account the effect of temperature on the change in volume of liquid metal and the resultant differences in the shape and size of formed shrinkage cavities. The aim of the article is to describe the influence that have material properties of the mold on the simulation results.

13

Mould components impact on structure and quality of elektron 21 alloy

Dybowski B., Kiełbus A., Jarosz R.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

17--23

EN

Magnesium alloys due to their low density and high strength-to-weight ratio are promising material for the automotive and aerospace industries. Many elements made from magnesium alloys are produced by means of sand casting. It is essential to investigate impact of the applied mould components on the microstructure and the quality of the castings. For the research, six identical, 100x50x20mm plates has been sand cast from the Elektron 21 magnesium casting alloy. Each casting was fed and cooled in a different way: one, surrounded by mould sand, two with cast iron chills 20mm and 40mm thick applied, another two with the same chills as well as feeders applied and one with only the feeder applied. Solid solution grain size and eutectics volume fraction were evaluated quantitatively in Met-Ilo program, casting defects were observed on the scanning electron microscope Hitachi S3400N. The finest solid solution grain was observed in the castings with only the chills applied. Non metallic inclusions were observed in each plate. The smallest shrinkage porosity was observed in the castings with the feeders applied.

14

Examination and elimination of defects in cone casting made of ductile cast iron

Guzik E., Łagowski M., Nowak-Dudek A., Niedzielski B.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 4

43--48

EN

In the scope of existing cooperation with the Foundry of Cast Iron ZM “WSK Rzeszów” Ltd. there was carried out research work of microstructure and mechanical properties in the walls of a cone casting made of ductile cast iron. The particular attention was being put to the search of the potential brittle phases which have deleterious effect on ductility and dynamic properties of highly strained use of the casting prone to the potential risk of cracks during the highly strained use.

15

Klasyfikacja wad struktury metalowych odlewów kompozytowych z nasycanym zbrojeniem

Gawdzińska K., Nagolska D., Szweycer M.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 1s

39--46

PL

Definicja kompozytu [1] określa materiał kompozytowy idealny o doskonałej budowie. W rzeczywistych materiałach kompozytowych mamy na ogół do czynienia z budową niedoskonałą – materiały kompozytowe zawierają różnorodne wady [2, 3–5], szczególnie kiedy rozpatrujemy kompozyty wytwarzane przez odlewanie. Odlewy bowiem charakteryzują się specyficzną budową związaną z przebiegiem procesu ich wytwarzania. W przypadku odlewów z kompozytów metalowych, a szczególnie wytwarzanych przez nasycanie, brak jest klasyfikacji tych wad [2, 4]. Klasyfikacja wad odlewów z materiałów klasycznych (żeliwo, staliwo, stopy metali nieżelaznych) jest niewystarczająca i wymaga uzupełnienia o specyficzne wady wspomnianych tworzyw. Problem ten (zauważony podczas wytwarzania odlewów z metalowych kompozytów nasycanych w Instytucie Podstawowych Nauk Technicznych Akademii Morskiej w Szczecinie oraz w Instytucie Technologii Materiałów Politechniki Poznańskiej) stał się przyczyną podjęcia prac nad stworzeniem takiej klasyfikacji i w efekcie do powstania niniejszej propozycji, która przyczynić się może do poprawy jakości badanych materiałów, a co jest z tym związane, z ochroną środowiska.

16

Influence of blowing of argon on the cleanness of steel

Pribulová A.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 3

91-94

EN

The mechanical properties of steel components are controlled by the chemical composition and mechanical treatment to which the steel is submitted. Non-metallic inclusions have a very high influence on the steel quality but secondary metallurgy enables to reduce their content in the steel. Possibilities of secondary metallurgy are relatively extensive but financial situation in Slovak foundries does not enable to make investments in secondary metallurgy in the near future. Accessible means for influencing of steel quality is injection of an inert gas. Main goal of experiments described in the article was verify the influence of blowing of argon into the steel in an electric induction furnace on its cleanness. Duration and flow-rate of argon blowing have a very clearly influence on the final content of non-metallic inclusions. Minimum time of argon blowing necessary for reducing of content of non-metallic inclusions in one tonne electric induction furnace was more then 6 minutes and recommended argon flow rate was 10 litters per minute.

17

Classification of structure defects of metal matrix castings with saturated reinforcement

Gawdzińska K., Nagolska D., Szweycer M.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 3

29-36

EN

Definition of a composite [1] describes an ideal composite material with perfect structure. In real composite materials, structure is usually imperfect - composites contain various types of defects [2, 3-5], especially as the casted composites are of concern. The reason for this is a specific structure of castings, related to course of the manufacturing process. In case of metal matrix composite castings, especially regarding these manufactured by saturation, there is no classification of these defects [2, 4]. Classification of defects in castings of classic materials (cast iron, cast steel, non-ferrous alloys) is insufficient and requires completion of specific defects of mentioned materials. This problem (noted during manufacturing metal matrix composite castings with saturated reinforcement in Institute of Basic Technical Sciences of Maritime University Szczecin) has become a reason of starting work aimed at creating such classification. As a result, this paper was prepared. It can contribute to improvement of quality of studied materials and, as a consequence, improve the environment protection level.

18

Modeling of feeding of grey iron castings

Perzyk M., Gontarski T.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 4

187-193

EN

The aim of the paper was development and testing a new methodology for adjusting of simulation parameters of casting processes. Instead using production castings with limited shapes, the methodology utilizes especially designed virtual castings of arbitrary geometries, with rigging systems calculated according generally approved principles, based on industrial experience. The present work tests included risers for grey iron castings, designed according Karsay's recommendations; the simulations were made using the commercial software NovaFlow&Solid. The preliminary simulations have shown that the parameters, which are most important from the viewpoint of occurrence of the shrinkage defects, are the density change during solidification and the gravity influence. Further systematic simulations allowed to find that the feeding flow modeled in the computer program does fully correspond to those practical recommendations: the flow is too easy in vertical direction an to difficult in horizontal direction. Despite that, it was possible to formulate recommendations regarding settings of the above simulation parameters which would facilitate correct predictions of the shrinkage defects in grey iron castings: the influence of gravity should be 'high' and the density change between liquidus and solidus temperatures should be between 0 to 78 kg/m3, depending on the feeding distance.

19

Method for determining the formation of shrinkage defects in the castings

Dyja R., Sczygiol N.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 4

35-40

EN

Simple simulations of solidification of metals and alloys generally provide results for determining the temperature distribution in a given time or solidification time for the specific locations of the casting. These data allow to unambiguously determine the position of thermal centers. However, knowledge about the location of thermal centers is not synonymous with the information about the location of any shrinkage defects in the casting, because the physical behaviour of molten metal should be still considered. This paper presents authors' own method of predicting the formation of shrinkage defects in the castings, basing on solidification simulation results, taking into account the basic rules of behaviour of the molten metal. The effectiveness of the method has been tested on the basis of example simulations performed for the flat shape of the casting inlet systems. The advantage of the method is that it requires little additional computational effort. The article is summarized by conclusions reached on the basis of simulations, as well as the program for further work containing possible improvements of the algorithm.

20

Gears castings from ductile iron of improved abrasion wear resistance

Kopyciński D., Guzik E., Siuta A., Siuta K.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 4

73-76

EN

The aim of this study was to develop an industrial technological process for the manufacturing of castings from alloyed ductile iron characterized by improved resistance to abrasion wear. The outcome of the study was the implementation of developed technology under the industrial conditions of ASPAMET Foundry Plant and start up of production of a wide range of cast gears.