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1
Content available Degradation of Creep Resistant Ni - alloy During Aging at Elevated Temperature Part II: Structure Investigations
Kaczorowski M., Skoczylas P., Krzyńska A.
Archives of Foundry Engineering
|
2015
|
Vol. 15, iss. 4
45--50
EN
The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K and 850K are presented. The structure investigation were carried out using conventional light-, scanning- (SEM) and transmission electron microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and growth of needle- and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γ" phases. Moreover, it can't be excluded that the least stable γ" phase is replaced with more stable γ' precipitates. TEM observations have disclosed differences in dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only, while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.
2
Content available Comparison of Austempered Ductile Iron and Manganese Steel Wearability
Kochański A., Krzyńska A., Chmielewski T., Stoliński A.
Archives of Foundry Engineering
|
2015
|
Vol. 15, iss. 1 spec.
51--54
EN
The results of comparison of the wear resistance of manganese steel X120Mn12, S235IR steel and austempered ductile iron ADI are presented. The aim of this study is to determine the possibility of replacing an item made of X120Mn12 steel with another material. For this purpose, all of the samples were measured for Brinell hardness. The samples were then tested for wear resistance in a specially designed test stand. The test resided in shot penning the surface of the test samples within the shot stream with the defined parameters. The test stand used in the test ensured the shot penning parameter stability. The test samples underwent multiple tests in which shot penning occurred in reccurrent cycles. Three test limits were established for the present study: 60, 120 and 180 cycles. The wear resistance measure in this study was the decrease in the tested sample’s weight expressed in grams and calculated for a unit of the shot-penned surface. The obtained results confirmed the possibility of using ADI as a possible replacement of manganese steels in specific cases. Of the eight types of the samples tested, the two ADI samples exhibited abrasion resistance which was comparable to that of the reference sample, while one exhibited better resistance. What constitutes the optimal chemical composition and the corresponding optimal heat treatment for particular cases remains an issue for further research.
3
Content available The Mechanism of Solid State Joining THA with AlMg3Mn Alloy
Kaczorowski M., Goroch O., Krzyńska A.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 2
37--42
EN
The results of experimental study of solid state joining of tungsten heavy alloy (THA) with AlMg3Mn alloy are presented. The aim of these investigations was to study the mechanism of joining two extremely different materials used for military applications. The continuous rotary friction welding method was used in the experiment. The parameters of friction welding process i.e. friction load and friction time in whole studies were changed in the range 10 to 30kN and 0,5 to 10s respectively while forging load and time were constant and equals 50kN and 5s. The results presented here concerns only a small part whole studies which were described elsewhere. These are focused on the mechanism of joining which can be adhesive or diffusion controlled. The experiment included macro- and microstructure observations which were supplemented with SEM investigations. The goal of the last one was to reveal the character of fracture surface after tensile test and to looking for anticipated diffusion of aluminum into THA matrix. The results showed that joining of THA with AlMg2Mn alloy has mainly adhesive character, although the diffusion cannot be excluded.
4
Content available Properties and Structure of High-Silicone Austempered Ductile Iron
Krzyńska A., Kochański A.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 2
91--94
EN
The results presented in this paper are a continuation of the previously published studies. The results of hest treatment of ductile iron with content 3,66% Si and 3,80% Si were produced. The experimental castings were subjected to austempering process for time 30, 60 and 90 minutes at temperature 300oC. The mechanical properties of heat treated specimens were studied using tensile testing and hardness measurement, while microstructures were evaluated with conventional metallographic observations. It was again stated that austempering of high silicone ferritic matrix ductile iron allowed producing ADI-type cast iron with mechanical properties comparable with standard ADI.
5
Content available Highsilicone Austempered Ductile Iron
Kochański A., Krzyńska A., Radziszewski T.
Archives of Foundry Engineering
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2014
|
Vol. 14, iss. 1
55--58
EN
Ductile iron casts with a higher silicone content were produced. The austempering process of high silicone ductile iron involving different austempering times was studied and the results presented. The results of metallographical observations and tensile strength tests were offered. The obtained results point to the fact that the silicone content which is considered as acceptable in the literature may in fact be exceeded. The issue is viewed as requiring further research.
6
Content available Austenitization of FerriticDuctile Iron
Krzyńska A., Kochański A.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 4
49--54
EN
Austenitization is the first step of heat treatment preceding the isothermal quenching of ductile iron in austempered ductile iron (ADI) manufacturing. Usually, the starting material for the ADI production is ductile iron with more convenient pearlitic matrix. In this paper we present the results of research concerning the austenitizing of ductile iron with ferritic matrix, where all carbon dissolved in austenite must come from graphite nodules. The scope of research included carrying out the process of austenitization at 900oC using a variable times ranging from 5 to 240 minutes,and then observations of the microstructure of the samples after different austenitizing times. These were supplemented with micro-hardness testing. The research showed that the process of saturating austenite with carbon is limited by the rate of dissolution of carbon from nodular graphite precipitates.
7
Content available Searching for Better Properties of ADI
Krzyńska A.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 1 spec.
91--96
EN
The results of study of austempered ductile iron using different methods of austempering are presented. Except changing time, temperature of austenitizing and isothermal quenching, direct quenching, two-step quenching followed solution heat treatment (austenitizing) was proposed. The goal of this paper is to discuss the results obtained for ductile cast iron subjected two step austempering. Ultimate tensile strength, elongation, hardness, and fracture toughness, thermal stability were compared. Two-step quenching method of hardening seems to be promising.
8
Content available The strengthening of weight heavy alloys during heat treatment
Kaczorowski M., Skoczylas P., Krzyńska A., Kaniewski J.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 4
75-80
EN
The results of studies of W-Ni-Co-Fe experimental alloy, with chemical composition assuring a possibility of producing Ni-based supersaturated solid solution are presented. The alloy was prepared from tungsten, nickel, cobalt and iron powders which were first mixed then melted in a ceramic crucible where they slowly solidified in hydrogen atmosphere. Next specimens were cut from the casting and heated at a temperature 950oC. After solution treatment the specimens were water quenched and then aged for 20 h at a temperature 300oC. The specimens were subjected to microhardness measurements and structure investigations. The latter included both conventional metallography and SEM observations. Moreover, for some specimens X-ray diffractometry studies and TEM investigations were conducted. It was concluded that quenching lead to an increase of tungsten concentration in nickel matrix which was confirmed by Ni lattice parameter increase. Aging of supersaturated solid solution caused strengthening of the Ni-based matrix, which was proved by hardness measurements. The TEM observation did not yield explicit proofs that the precipitation process could be responsible for strengthening of the alloy.
9
Content available Ocena możliwości wykorzystania w odlewnictwie gipsu syntetycznego uzyskanego podczas procesu mokrego odsiarczania spalin w energetyce
Biernacki R., Haratym R., Krzyńska A.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 1s
5--8
PL
Przedstawiono analizę możliwości wykorzystania w odlewnictwie gipsu odpadowego (syntetycznego) uzyskiwanego w procesie odsiarczania spalin w energetyce. Energetyka jest jednym z największych producentem SO2. W celu ochrony środowiska i obniżenia ilości zanieczyszczeń stosuje się odsiarczanie spalin metodą mokrą. W wyniku tego procesu powstaje gips odpadowy, który może być stosowany w praktyce. Przeprowadzono badania, w wyniku których określono sposoby przygotowania tego gipsu do wykonywania form odlewniczych. W artykule oceniono skład chemiczny, wytrzymałość i przepuszczalność form z uzyskanego gipsu syntetycznego, porównano je z właściwościami gipsu odlewniczego GoldStar XL oraz właściwościami form ceramicznych. Zbadano strukturę gipsów, wykonano badania na derywatografie oraz określono energochłonność procesu wytwarzania gipsu odpadowego w instalacji mokrego odsiarczania. Po analizie zebranych danych można stwierdzić, że gips syntetyczny może być używany jako materiał na formy odlewnicze. Nie obserwuje się znaczącego spadku najważniejszych właściwości, a z drugiej strony istnieje wiele dodatkowych korzyści, w tym niskie zużycie energii, obniżenie kosztów i zmniejszenie wpływu na środowisko.
EN
This article investigates possible use of waste gypsum (synthetic), recovered via flue-gas desulfurization from coal-fired electric power plants, in foundries. Energy sector, which in Eastern Europe is mostly composed from coal-fired electric power plants, is one of the largest producers of sulfur dioxide (SO2). In order to protect the environment and reduce the amount of pollution flue-gas desulfurization (FGD) is used to remove SO2 from exhaust flue gases of fossil-fuel power plants. As a result of this process gypsum waste is produced that can be used in practical applications. Strength and permeability tests have been made and also in-depth analysis of energy consumption of production process to investigate ways of preparing the synthetic gypsum for casting moulds application. This paper also assesses the chemical composition, strength and permeability of moulds made with synthetic gypsum, in comparison with moulds made with traditional GoldStar XL gypsum and with ceramic molds. Moreover examination of structure of synthetic gypsum, the investigations on derivatograph and calculations of energy consumption during production process of synthetic gypsum in wet flue-gas desulfurization were made.
10
Content available The influence of Fe content on spreading ability of tungsten heavy alloys matrix on tungsten surface
Kaczorowski M., Skoczylas P., Krzyńska A.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 3 spec.
103--106
EN
The results of experimental study of tungsten spreading ability with W-Ni-Co-Fe matrix are presented. The aim of these investigations was to see how Fe concentration in W – Ni – Co matrix influences the wettability of tungsten grains during liquid phase sintering. Four green compact specimens containing 50%W, 10%Co and Ni + Fe = 40% but with different Ni to Fe ratio were prepared. The cylindrical specimen 5mm diameter and 5mm height were put on clean pure tungsten substrate and then 20 minutes heated at 1520ºC in hydrogen atmosphere. After heating the specimens were carefully measured and then the specimens for structure observations were prepared. It was concluded, that increase of Fe content decrease the melting temperature of W – Ni – Co alloy. The melting point decrease caused by Fe content increase substantially the spreading ability of tungsten substrate with W – Ni – Co alloy. Metallography investigations showed some microstructure changes in “reaction zone” identified in tungsten substrate – (WNi40-xCo10Fex) interface. The results of the study confirmed our earlier observations that even relative small Fe addition promotes Weight Heavy Alloys (WHA) liquid phase sintering.
11
Content available remote The comparative studies of ADI versus Hadfield cast steel wear resistance
Skoczylas P., Krzyńska A., Kaczorowski M.
Archives of Foundry Engineering
|
2011
|
Vol. 11, iss. 2
123-126
EN
The results of comparative studies of wear resistance of ADI versus high manganese Hadfield cast steel are presented. For evaluation of wear resistance three type of ADI were chosen. Two of them were of moderate strength ADI with 800 and 1000MPa tensile strength while the third was 1400MPa tensile strength ADI. The specimens were cut from ADI test YII type casting poured and heat treated in Institute of Foundry in Krakow. The pin on disc method was used for wear resistance experiment. The specimens had a shape of 40mm long rod with diameter 6mm. The load and speed were 100N and 0,54m/s respectively. It was concluded that the wear resistance of ADI is comparable with high manganese cast steel and in case of low tensile grade ADI and is even better for high strength ADI than Hadfield steel.
12
Content available remote The changes of ADI structure during high temperature annealing
Krzyńska A., Kaczorowski M.
Archives of Foundry Engineering
|
2010
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Vol. 10, iss. 1 spec.
87--92
EN
The results of structure investigations of ADI during it was annealing at elevated temperature are presented. Ductile iron austempered at temperature 325 °C was then isothermally annealed 360 minutes at temperature 400, 450, 500 and 550 °C. The structure investigations showed that annealing at these temperatures caused substantial structure changes and thus essential hardness decrease, which is most useful property of ADI from point of view its practical application. Degradation advance of the structure depends mainly on annealing temperature, less on the time of the heat treatment. It was concluded that high temperature annealing caused precipitation of Fe3C type carbides, which morphology and distribution depend on temperature. In case of 400 °C annealing the carbides precipitates inside bainitic ferrite lath in specific crystallographic planes and partly at the grain boundaries. The annealing at the temperature 550 °C caused disappearing of characteristic for ADI needle or lath – like morphology, which is replaced with equiaxed grains. In this case Fe3C carbides take the form very fine precipitates with spheroidal geometry.
13
Content available remote On the possibility of replacing high manganese cast steel military vehicle track pads with ADI
Kaczorowski M., Skoczylas P., Krzyńska A.
Archives of Foundry Engineering
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2010
|
Vol. 10, iss. 1 spec.
81--86
EN
The theoretical considerations of possibility replacing of high manganese cast steel used for military vehicle track pads with ADI are presented. Except these considerations, comparative investigations including tensile strength tests hardness measurements and impact resistance were included. Moreover, the structure investigation was carried out using either conventional light metallography and scanning (SEM). The last one was applied for fractography investigations, the aim of which was to discover the mode of fracture. The discussion of experimental results leads to conclusion that ADI, known as high friction resistant, looks to be concurrent material with respect to high manganese cast steel used now for tang track pads.
14
Content available remote Low alloy steel versus ADI - differences and similarities
Krzyńska A., Kaczorowski M.
Archives of Foundry Engineering
|
2009
|
Vol. 9, iss. 1
151-156
EN
The results of comparison between the microstructure of selected bainitic low alloy steel and austempered ductile iron ADI are presented. The aim of the comparison was to find out differences and similarities existing in these iron carbon commercial alloys. In this paper our own results on ADI structure and literature data were used. It follows from discussion presented here that both microstructure and properties of ADI are very close that which are observed in low alloy carbon steel. Moreover, we suggest that there is no so doubt to treat ADI mechanical properties as steel containing nodular inclusions of graphite.
15
Content available remote The studies of nodular graphite cast iron early stages austempering
Krzyńska A., Kaczorowski M.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 4
87-92
EN
The results of early stage of ductile cast iron austempering are presented. The aim of the investigations was to look closer into the structure - mechanical properties relationships of this very attractive cast material. The experiment was carried out with enriched with Cu EN-GJS-500-7 grade ductile iron. The specimens were first solution heat treated 1 hour in 910oC and then isothermally quenched for different time in molten tin at the temperature 275°C. The mechanical properties of as cast and heat treated specimens were tested to evaluate tensile Rm and yield strength R p, 0.2 and elongation A5. Additionally hardness measurements were carried out using Brinell-Rockwell method. Structure of the specimens both as cast and after austempering was studied using conventional light microscopy. Moreover, scanning electron microscopy (SEM) was applied for fracture surface observations. It was concluded that short time low temperature austempering lead to formation martensitic microstructure characterized by very high hardness with almost zero ductility. The lack of ductility make the material very sensitive to any structure defects which work as a stress concentrators which strongly influence the strength of heat treated ductile iron specimens.
16
Content available remote The structure and mechanical properties of heat treated Al-Zn-Cu-Mg type alloy
Kaczorowski M., Krzyńska A.
Archives of Foundry Engineering
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2008
|
Vol. 8, iss. 1 spec.
163--168
EN
The results of precipitation hardening 7075 type cold worked alloy are presented. The aim of the study was to elaborate an Al-Zn-Cu-Mg type light alloy for special application. The most important was to propose the heat treatment parameters which would allow reach the extremely high tensile properties with good ductility. These properties was as follow: tensile strength > 640MPa, Rp, 02 > 600MPa and A5 no less than 8%. To meet these properties we propose the solution heat treatment at the temperature 520 °C with cooling in cold water. The temperature 125°C was chosen for aging. The different aging time was applied for the specimen after solution heat treatment followed with quenching in cold water. The mechanical properties of heat treated specimens were tested in tension and using hardness measurement. Besides the conventional Metallography, scanning (SEM) and transmission electron microscopy (TEM) were applied for structure observations. In case of the last one we used either microscopy observations where tilting experiment was used and selected area electron diffraction (SAD).
17
Content available remote The mystery of ADI
Krzyńska A., Kaczorowski M.
Archives of Foundry Engineering
|
2007
|
Vol. 7, iss. 4
111-114
EN
The considerations of ADI strengthening mechanisms based on results of previous structure investigations are presented. The aim of this elaboration was to discuss which mechanism looks to be most responsible for strengthening of ADI. It was concluded that the high strength of ADI which matrix consist mostly ferrite, austenite and sometimes some amount of martensite is caused by strengthening these three phases. Neglecting high carbon martensite which strength properties are nothing surprising, it is proposed that different mechanism of strengthening are responsible for ferrite and austenite strength increase. In case first of these phases strengthening is caused mainly by strain hardening. It is evidenced with very high dislocations and dislocation loops density which are typical in case of ferrite grains. The mechanism of austenite strengthening is more complicated. First of all hardening of austenite is connected with high supersaturation with carbon. The effect of strengthening is additionally increased with grains refinement caused by twinning and formation of stacking faults. The first of them supply extra coherent grain boundaries and the second lead to distortion of perfect lattice structure. It looks from the analysis, that strengthening rather soft and ductile phases which are ferrite and austenite is high enough to explain high strength properties of ADI.
18
Content available remote The influence of chemical composition on the properties and structure Al-Si-Cu(Mg) alloys
Kaczorowski M., Krzyńska A.
Archives of Foundry Engineering
|
2007
|
Vol. 7, iss. 2
129-134
EN
The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg) type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM) and transmission (TEM) electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg) type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.
19
Content available remote Mechanical properties and structure of austempered ductile iron -ADI
Kaczorowski M., Krzyńska A.
Archives of Foundry Engineering
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2007
|
Vol. 7, iss. 1
161-166
EN
The results of experimental study of austempered ductile iron are presented. The aim of the investigations was to look closer into the structure – mechanical properties relationships of this very attractive cast material. The experiment was carried out with 500 7 grade ductile iron, which was austempered using different parameters of heat treatment. The specimens were first solution treated 1 hour in 910°C and then isothermally quenched for different time in silicon oil bath of temperature 275, 325, 300 and 350°C. The mechanical properties heat treated specimens were tested in tensile to evaluate yield stress R_e, 0.2, tensile strength R_m and elongation A_10. Additionally hardness of heat treated samples was measured using Brinell-Rockwell hardness tester. Structure of the specimens was studied either with conventional metallography, scanning (SEM) and transmission (TEM) electron microscopy. It followed from the study that conventional grade ductile iron enabled to produce both low and high strength ADI, depend on heat treatment parameters. As expected the low temperature isothermal quenching produced higher strength ADI compare to the same ductile iron but austempered at 350°C. It was discovered however, that low yield strength ADI obtained for short time quenching at 275°C exhibited high strengthening effect while strained in tensile. So it was concluded that this had to by cause by large amount of untransformed austenite, which FCC lattice is characterized by high strengthening coefficient.
20
Content available remote Własności mechaniczne i struktura żeliwa z grafitem mieszanym po dwustopniowym hartowaniu izotermicznym
Krzyńska A., Kaczorowski M.
Archiwum Odlewnictwa
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2006
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R. 6, nr 18/2
89--94
PL
W artykule zaprezentowano wyniki badań otrzymane w kolejnej próbie dwustopniowego hartowania żeliwa [1,2] tym razem z grafitem mieszanym, tj. sferoidalnym i wermikularnym. Z odlewów wycięto mini próbki wytrzymałościowe o średnicy w części pomiarowej 4mm. Próbki austenityzowano 60 min. w temperaturze 900°C, a następnie przeprowadzono dwa warianty dwustopniowego hartowania izotermicznego. Pierwszy z nich obejmował hartowanie izotermiczne w temperaturze T1wI = 300°C przez czas 10 i 30 min. a następnie w temperaturze T2wI = 250°C przez okres 45, 90 i 120 min. Drugi wariant obejmował hartowanie izotermiczne wpierw w temperaturze T1wII = 250°C przez czas 30 i 60 min. a następnie w temperaturze T2wII = 300°C przez 30, 60 i 90 min. Hartowanie izotermiczne „wysokotemperaturowe” (300°C) było przeprowadzone w ciekłej cynie natomiast „niskotemperaturowe” (250°C) w oleju silikonowym. Dla każdego wariantu obróbki cieplnej wykonano po trzy próbki, które poddano badaniom na maszynie wytrzymałościowej celem określenia Rm, R0,25, badaniom twardości oraz obserwacjom metalograficznym.
EN
The results of two stage austempered cast iron with mixed graphite (nodular and vermicular) were presented. The small samples 4mm in diameter were solution heat treated for 60min. at the 900ºC. Then they were austempered in two manners. In first the samples were first 10 and 30 min. quenched at the temperature T1wI=300ºC and subsequently austempered at T2wI =250ºC for 45, 90 and 120 minutes. In the second variant the samples were first 30 and 60min. isother-mally quenched at T1wII =250ºC and then 30, 60 and 90 minutes austempered at the temperature T2wII=300ºC. The “high-temperature” (300ºC) austempering were performed at molten tin bath and the “low temperature” (250ºC) austempering at silicone oil. Three specimens were used for each variant of heat treatment. These specimens were subjected to tensile test experiment for Rm, R0,2 i A5 evaluation. Moreover the hardness measurements and metallography observations were carried out.
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