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1

The Melting Process and its Impact on the Properties of High-Chromium Cast Iron and the Economic Calculation

Mędoń Jan, Szczęsny Andrzej, Ziółkowski Eugeniusz, Guzik Edward, Czarny M., Kopyciński Dariusz

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

54--64

EN

The subject of this study is to show that the parameters of the melting process of high chromium cast iron affect the cost of casting and the properties of the cast iron. The analysis of the quality of the casting and its price was conducted in terms of the metal charge of high chromium cast iron. As is well known, in order to obtain the correct structure of the casting, and thus good strength properties, it is necessary to use clean batch components free of undesirable impurities. Unfortunately, the quality of the metal charge is proportional to its price. Thus, the use of expensive batch components offers the possibility of obtaining healthy and meeting the strength properties of castings. However, there is a flaw in this approach. And it is from the point of view of economics that production plants are forced to look for savings. Expensive feedstock materials are replaced by cheaper counterparts giving the possibility of obtaining castings with similar properties often, however, at the cost of increased inferior quality. It seems that a way out of this situation is to introduce a modification procedure into the alloyed iron manufacturing technology. The selected modifiers should affect the fragmentation of the structure of the primary austenite. At this point, it can be hypothesized that this will result in the elimination of hot cracking in high chromium cast iron. The industrial research carried out at the "Swidnica" Foundry Ltd. made it possible to show by means of the Althoff-Radtke method that by using the modification of the liquid metal of the so-called "inferior and cheaper" composition of the metal charge, a reduction in the occurrence of hot cracks and shrinkage cavities can be achieved. In addition, iron-niobium modification not only reduced the formation of casting defects in castings, but also slightly improved the impact strength of high-chromium cast iron. The work was written as part of an implementation PhD.

2

Improving grinding ball lifespan and efficiency through hardenability modelling and optimization

Aissat Sahraoui, Safa Ali

Advances in Materials Science

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2023

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Vol. 23, nr 3(77)

5--20

EN

Grinding balls are spherical or cylindrical components used in grinding and milling operations to reduce the size of particles and achieve a finer product. They are made of high chromium white cast iron (HCWCI) and used in a variety of industrial processes. The efficiency of the grinding process is heavily influenced by the properties of the grinding balls, including their composition, size, and hardness. As such, there is ongoing research and development to improve the performance and durability of grinding balls, with the aim of countering the extreme conditions of wear and impact that cause a reduction in their lifespan. This study involved austenitizing balls with diameters of 50 mm and 70 mm at temperatures of 950°C and 1050°C, followed by quenching using both oil and compressed air. By exploiting the experimental HRC hardness results obtained in this work, the study aims to find a mathematical model relating the response (hardenability) to the main effects (austenitization temperature, quenching medium, and diameter balls) and their interactions. Analysis of variance (ANOVA) was used to establish the statistical significance parameters and an optimization of response by the best sub-models method and by the desirability function is realized in the second part of this work. It seems that the austenitization temperature and the size of the balls have a stronger impact on the hardenability of the balls than the cooling rate (quenching medium) by reducing the hardness difference between the surface and the medium of the ball to minimal values.

3

Investigation on the influence of tempering on microstructure and wear properties of high alloy chromium cast iron

Younes Rassim, Sadeddine Abelhamid, Bradai Mohand Amokrane, Aissat Sahraoui, Benabbas Abderrahim

Advances in Materials Science

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2021

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Vol. 21, nr 2(68)

65--76

EN

Mechanical properties, wear resistance and impact resistance of a high-alloy chromium cast iron used in the fabrication of grinding balls have been studied. A rank of tempering heat treatments under several temperatures 500°C, 525°C, 550°C and 575°C was performed after austenitized at 1050°C. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) techniques have been used to characterize the microstructures and identify the phases. The wear balls tests were conducted in a rotating drum with a velocity 0.5 r/s. The tribological tests were carried out by evaluated a weight loss as function time. The measurement of the rebound resilience was determined by Charpy impact tests. The results of XRD showed the presence of the martensite, carbides type M7C3 and M2C for all tempering heat treated. The hardness of the sample increased after the tempering and reach nearly 65 HRC at 1050°C. In another hand, it decreased after the tempering treatment it could be explained by precipitation of the carbides type M2C.

4

The effect of temperature on the hardness of high-alloy carbide-chromium alloys surfaced with flux-cored strips

Woronczuk Aleksander P., Żudra Aleksander P.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2019

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Vol. 63, No. 4

39--46

EN

The development of surfacing materials deposited on elements exposed to extreme wear at high temperature is based on investigating the correlation between the hot hardness of the weld deposit and its alloy system. The article discusses the methodology and results concerning the hot hardness of deposited high-chromium cast irons characterised by various doping degrees, e.g. 450H30M, 500H22B7, 500H22B7M7W2F and 300H25S3N2G2 as well as nickel-carbide-chromium alloy 500H40N40S2GRC. Related tests revealed that the hot hardness of the weld deposit depends primarily on the presence and types of carbides formed in the weld pool. The hardness of relatively low-alloy high-chromium cast irons decreases along with an increase in temperature and increases along with an chromium content of up to 30% and a carbon content of up to 5%. Chromium, niobium, molybdenum, tungsten and vanadium-surface alloyed alloys retain their hardness up to a temperature of 650 °C. In terms of the above-named alloys, an important role is played by niobium, acting as a modifying agent and moderating the growth of primary chromium carbides and forming hard cubic niobium carbide. Because of the high content of higher chromium carbides in the nickel-based matrix, the nickel-carbide-chromium alloy is characterised by high hardness at a temperature of up to 650 °C.

PL

Rozwój materiałów do napawania części pracujących w ekstremalnych warunkach zużycia w podwyższonych temperaturach opiera się na badaniu zależności między twardością na gorąco stopiwa a jego układem stopowym. W pracy przedstawiono metodologię i wyniki badań twardości na gorąco napawanych żeliw wysokochromowych o różnym stopniu domieszkowania, takich jak 450H30M, 500H22B7, 500H22B7M7W2F, 300H25S3N2G2, a także stopu niklowo-węglikowo-chromowego 500H40N40S2GRC. Ustalono, że twardość na gorąco stopiwa w dużej mierze zależy od obecności i rodzaju węglików, które powstają w jeziorku spawalniczym. W przypadku stosunkowo niskostopowych żeliw wysokochromowych twardość spada wraz ze wzrostem temperatury i wzrasta wraz z zawartością chromu do 30% i węgla do 5%. Stopy stopowane chromem, niobem, molibdenem, wolframem i wanadem zachowują wysoką twardość do temperatury 650°C. Dla tych stopów ważną rolę odgrywa niob, który działa jak modyfikator, spowalniając wzrost pierwotnych węglików chromu i tworząc twardy sześcienny węglik niobu. Wysoką twardość do temperatury 650°C utrzymuje stop niklowo-węglikowo-chromowy dzięki wysokiej zawartości wyższych węglików chromu w matrycy na bazie niklu.

5

Morphology and Material Properties of Carbides in High (24%) Chromium Cast Iron

Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Jacek M., Radoń M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

77--80

EN

The present paper is a presentation of results of a study on morphology, chemical composition, material properties (HVIT, HIT, EIT), and nanoindentation elastic and plastic work for carbide precipitates in chromium cast iron containing 24% Cr. It has been found that the carbides differ in chemical composition, as well as in morphology and values characterizing their material properties. The carbides containing the most chromium which had the shape of thick and long needles were characterized with highest values of the analyzed material properties.

6

Effect of Titanium Inoculation on Tribological Properties of High Chromium Cast Iron

Siekaniec D., Kopyciński D., Szczęsny A., Guzik E., Tyrała E., Nowak A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

143--146

EN

The present investigation focuses on the study of the influence of titanium inoculation on tribological properties of High Chromium Cast Iron. Studies of tribological properties of High Chromium Cast Iron, in particularly the wear resistance are important because of the special application of this material. High Chromium Cast Iron is widely used for parts that require high wear resistance for example the slurry pumps, brick dies, several pieces of mine drilling equipment, rock machining equipment, and similar ones. Presented research described the effects of various amounts of Fe-Ti as an inoculant for wear resistance. The results of wear resistance were collated with microstructural analysis. The melts were conducted in industrial conditions. The inoculation was carried out on the stream of liquid metal. The following amount of inoculants have been used; 0.17% Fe-Ti, 0.33% Fe-Ti and 0.66% Fe-Ti. The tests were performed on the machine type MAN. The assessment of wear resistance was made on the basis of the weight loss. The experimental results indicate that inoculation improve the wear resistance. In every sample after inoculation the wear resistance was at least 20% higher than the reference sample. The best result, thus the smallest wear loss was achieved for inoculation by 0.66% Fe-Ti. There is the correlation between the changing in microstructure and wear resistance. With greater amount of titanium the microstructure is finer. More fine carbides do not crumbling so quickly from the matrix, improving the wear resistance.

7

Effect of Different Inoculants on Impact Toughness in High Chromium Cast Iron

Siekaniec D., Kopyciński D., Guzik E., Tyrała E., Nowak A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

85--88

EN

The present work, presented the study of effect of different inoculants on impact toughness in High Chromium Cast Iron. The molds were pouring in industrial conditions and samples were tested in laboratory in Faculty of Foundry Engineering at AGH. Seven samples were tested - one reference sample, three with different addition of Fe-Ti, and three with different addition of Al. The samples were subjected to impact toughness on Charpy hammer and the hardness test. The presented investigations indicate that for the each inoculant there is an optimal addition at which the sample obtained the highest value of impact toughness. For the Fe-Ti it is 0.66% and for Al is 0.17%. Of all the examined inoculants best results were obtained at a dose of 0.66% Fe-Ti. Titanium is a well-known as a good modifier but very interesting results gives the aluminum. Comparing the results obtained for the Fe-Ti and Al can be seen that in the case of aluminum hardness is more stable. The hardness of all samples is around 40-45 HRC, which is not high for this type of cast iron. Therefore, in future studies it is planned to carry out the heat treatment procedure that may improves hardness.

8

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.

9

Abrasion Wear Behavior of High-chromium Cast Iron

Pokusová M., Brúsilová A., Šooš L'., Berta I.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 2

69--74

EN

High-chromium cast irons are used as abrasion resistant materials. Their wear resistance depends on quantity of carbides and the matrix supporting these carbides. The paper presents the results of cast irons of chemical composition (in wt. %) 19–22 Cr and 2–4.5 C alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve their toughness, which were tested in working conditions of ferroalloys crushing. Tests showed that these as-cast chromium cast irons with mostly austenitic matrix achieved the hardness of 38-45 HRC, but their relative abrasion resistance Ψ ranged from 1.3 to 4.6, was higher comparing to the tool made from the X210Cr12 steel heat treated on hardness 61 HRC. The transformation of austenite into martensite occurs not only at the worn strained areas (on a surface of scratch) but also in their neighbourhood. Due to the work hardening of relatively large volumes of transformed austenite the cast iron possesses high abrasion resistance also on the surfaces where low pressures are acting. The tough abrasion-resistant cast iron well proved for production of dynamic and wear stressed castings e.g., crusher hammers, cutting tools for ceramic etc.

10

The Effect of Addition of Titanium on The Structure and Properties of High Chromium Cast Iron

Kopyciński D., Guzik E., Siekaniec D., Szczęsny A.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 3

35--38

EN

The paper presents results of Ti-addition to High Chromium Cast Iron (HCCI) on the structure and selected mechanical properties. For this study casted two sets of cylinders with dimensions ø20 mm, ø15 mm x 250 mm, for the High Chromium Cast Iron (HCCI) and with the 4% by mass Ti-addition. Melts were performed in the induction furnace crucible capacity of 15 kg. During the heats the cup with installed S type thermocouple was poured to record the cooling curves. The cylinders were subjected to the static bending strength test. Samples for the test microstructure and Rockwell hardness were cut from the cylinders. The study shows that the addition of titanium had an impact on the structure and thus the properties of High Chromium Cast Iron (HCCI). In subsequent studies, through an appropriate choice of chemical composition and proper process control, it is planned to obtain in the structure the titanium carbides TiC and chromium carbides with type (Cr, Fe)7C3.

11

Przykład obróbki cieplnej odlewów z żeliwa wysokochromowego

Siekaniec D., Szczęsny A., Kopyciński D.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4 spec.

109--112

PL

Żeliwo wysokochromowe jest powszechnie stosowanym materiałem w przemyśle górniczym i mineralnym, gdzie wymagana jest duża odporność na zużycie ścierne. Swoje dobre właściwości zawdzięcza obecności w mikrostrukturze twardych węglików. Żeliwo chromowe poddawane hartowaniu ma w praktyce osnowę austenityczną, austenityczno-perlityczną lub perlityczną. Istotnym procesem w czasie obróbki cieplnej jest tzw. destabilizacja austenitu, jest on ważny ponieważ dopiero po jego zajściu może nastąpić przemiana martenzytyczna. W zależności od szybkości chłodzenia, które następuje po procesie destabilizacji austenitu, może powstać perlit, bainit i martenzyt. Przeprowadzone badania dotyczyły określenia wpływu szybkości chłodzenia odlewów z żeliwa wysokochromowego po obróbce cieplnej, na mikrostrukturę i twardość. Badaniu zostało poddane żeliwo wysokochromowe o zawartości 27%Cr i 2,7%C. Przeprowadzono zabieg hartowania z temperatury 950 °C w czasie 4h, następnie odlewy poddano trzem wariantom chłodzenia – w wodzie, w kąpieli solnej i na powietrzu. Zbadano i porównano mikrostrukturę oraz twardość odlewów dla różnych wariantów chłodzenia.

EN

High Chromium Cast Iron (HCCI) is widely use in mining and mineral industry, where abrasive resistance is a principal requirement. Its good properties thanks to the hard eutectic carbides occurring in the microstructure. The effect of heat treatment on HCCI was a subject of many research. High Chromium Cast Iron have an austenitic, austenitic-pearlitic or pearlitic matrix. An important process during the heat treatment is austenite destabilization, thus until after it conduct the martensitic transformation can occur. Depending on the cooling rate that follows the process of destabilization of austenite, perlite, bainite and martensite may form. The present work, aimed at studying the influence of cooling rate after heat treatment, on the microstructure and hardness. The study were carry out on samples of High Chromium Cast Iron containing 27%Cr i 2,7%C. Samples were subjected to the tempering treatment at the temperature of 950°C for 4 hours and three variants of cooling – in water, in a salt bath and on air. Examined and compared the microstructure and hardness of castings for different variants of cooling.

12

The Influence of the Pouring Temperature on the Structure and Mechanical Properties of High-Chromium Cast Iron

Kopyciński D., Siekaniec D.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 4 spec.

63--66

EN

The article presents the results of the influence of pouring temperature on the structure and selected properties of high-chromium cast iron. The study was performed on two different pouring temperatures 1490°C and 1460°C for cast iron of the same chemical composition. Melts were performed in the induction furnace crucible capacity of 15 kg located in the Department of Engineering Alloys and Composites in Foundry Engineering Faculty of AGH. For each temperature cast 2 sets of rollers with dimensions ø30mm, ø20mm, ø15mm x 250mm. During the heats poured cup with installed S type thermocouple to record the cooling curves. Rollers put to the static bending strength test. Samples were cut from the rollers for the test microstructure. The study shown that the pouring temperature has a significant impact on the way of crystallization of high-chromium cast iron and consequently, on the microstructure and mechanical properties. It follows that, by appropriate selection of the pouring temperature can control certain properties of the casting.

PL

W pracy przedstawiono wyniki badań wpływu temperatury odlewania na strukturę i wybrane właściwości wytrzymałościowe żeliwa wysokochromowego. W ramach badań wykonano dwa wytopy z różną wartością temperatury odlewania 1490 °C i 1460 °C, dla żeliwa o tym samym składzie chemicznym. Wytopy wykonano w piecu indukcyjnym o pojemności tygla 15 kg znajdującym się w Katedrze Inżynierii Stopów i Kompozytów Odlewanych na Wydziale Odlewnictwa AGH. Dla każdej temperatury odlano 2 zestawy wałków o wymiarach ø30 mm, ø20 mm, ø15 mm x 250 mm. Podczas wytopów zalano kubki pomiarowe z termoelementem typu S do rejestracji krzywej krystalizacji i stygnięcia. Wałki poddano statycznej próbie wytrzymałości na zginanie. Następnie z wałków wycięto próbki do badania mikrostruktury. Z przeprowadzonych badań wynika, że temperatura odlewania ma istotny wpływ na sposób krystalizacji odlewu z żeliwa wysokochromowego, a w konsekwencji na mikrostrukturę i właściwości wytrzymałościowe. Wynika z tego, że przez odpowiedni dobór temperatury odlewania można sterować niektórymi właściwościami mechanicznymi odlewu.

13

Analysis of the High Chromium Cast Iron Microstructure after the Heat Treatment

Kopyciński D., Guzik E., Siekaniec D., Szczęsny A.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 3

43--46

EN

The article presents results of heat treatment on the high chromium cast iron. The study was carrying out on samples cut from the casting made from chromium cast iron. Those were hardened at different temperatures, then tempered and soft annealed. The heat treatment was performed in a laboratory chamber furnace in the Department of Engineering Alloys and Composites at Faculty of Foundry Engineering AGH. At each stage of the heat treatment the hardness was measured by Vickers and Rockwell methods, and the microscope images were done. Additionally based on images from the optical microscope the microstructure was assessed. Based on these results, the effect of hardening, tempering and soft annealing on the microstructure and hardness of high chromium cast iron was studied. Next the effects of different hardening temperatures on the properties of high chromium cast iron were compared. The study led to systemize the literature data of the parameters of heat treatment of high chromium cast iron, and optimal conditions for heat treatment was proposed for casts of similar properties and parameters.

14

The structure of abrasion-resisting castings made of chromium cast iron

Kopyciński D., Guzik E., Piasny S.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 1

61-64

EN

In this study presents the analyse of chrome iron cast structure (as-cast condition) which are used in rugged conditions abrasion-percussive and high temperature. While producing the casts of chrome iron major influence has been preserve the structure of technological process parameters. The addition to Fe-C-Cr alloy Ni, Mo or Cu and then proper heat treatment leads to the improvement of functional and mechanical cast qualities. Then it is possible to develop high mechanical properties which are recommended by PN-EN12513. As can it be seen from the above research silicon is an adverse chemical element in this kind of alloy cast iron. However, the reason of cracks appearing in chrome iron casts are phosphorus eutectic microareas. When the compound of Si and P reach the critical point, described in PN-88/H-83144 outdated standard, the microareas might appear.

15

Żeliwo wysokochromowe na łopatki rzutowe oczyszczarek wirnikowych

Rzadkosz S., Staszczak L.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/1

71-78

PL

Opisano główne mechanizmy zużycia ściernego oraz zasady doboru stopów odlewniczych odpornych na ścieranie. Więcej uwagi badawczej skierowano na żeliwo o zwiększonej zawartości chromu stosowanemu do wytwarzania łopatek rzutowych do oczyszczarek wirnikowych. Omówiono wpływ zawartosci składników tego żeliwa na jego odporność na ścieranie oraz na właściwości odlewnicze, decydujące o powstawaniu jam skurczowych i rzadzizn, które obniżają trwałość eksploatacyjną łopatek. Podano sposoby obróbki cieplnej łopatek z żeliwa wysokochromowego, której efektem jest zwięszenie twardości łopatek oraz zmniejszenie naprężeń własnych.

EN

The main mechanisms of attrition wear and the principles of the selection of wear resistant casting alloys have been described. More researches attention have been directed on high chromium cast iron usually applied for manufacturing impellers used in shot blasting machines. The results of investigation concerning influence of cast alloy ingredients contents on the wear-resistance and on the casting properties of the alloy, crucial for shrinkage cavity volume or porosity formation, which decreases of shot blasting impellers durability. The thermal treatment of shot blasting impellers have been proposed by the authors which resulted in increasing of impellers hardness and lowering of their own stresses.

16

High-chromium cast iron with higher ductility

Murgaš M., Pokusová M.

Archiwum Odlewnictwa

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2006

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R. 6, nr 18/2

171--176

EN

The cast iron with composition (in wt.%): C 2.6–2.8%, Cr 20–24%, Mo 0.7–1.5%, Ni 0.8-1.3%; 0.4-2% Mn, Si max. 1% with the trace amount of Ti and V was developed. Its foundry properties are very good and enable to cast the complex shaped castings with the section about 3 mm. The castings do not require the heat treatment, and in the range of wall section from 3 to 40 mm the as-cast material attains hardness from 47 to 53 HRC, ductility A5 of 1% minimally and is characterized by self-sharping effect.

PL

Badano żeliwo o składzie chemicznym (wg. %): C 2.6–2.8%, Cr 20–24%, Mo 0.7–1.5%, Ni 0.8-1.3%; 0.4-2% Mn, Si max. 1% ze śladową ilością tytanu i wanadu. Jego właściwości odlewnicze są bardzo dobre i umożliwiają wykonanie odlewów o złożonych kształtach z przekrojem około 3 mm. Odlewy nie potrzebują obróbki cieplnej i w przedziale grubości ścianki od 3 do 40 mm materiał ma twardość od 47 do 53 HRC, plastyczność A5 min 1% jest charakterystyczna wynikom samoostrzenia.

17

Wpływ wartości współczynnika przewodności cieplnej masy formierskiej na morfologię węglików w żeliwie 2,2%C - 22%Cr

Bieńko G., Drotlew A.

Archiwum Odlewnictwa

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2005

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R. 5, nr 15

33--38

PL

W artykule przedstawiono matematyczny opis zależności pomiędzy wybranymi parametrami stereologicznymi fazy węglikowej w ferrytycznym żeliwie wysokochromowym o zawartości 2,2% C i 22% Cr, a współczynnikiem przewodności cieplnej mas formierskich λ [W/m2K]. Stwierdzono, że kierunki wpływu zmian parametrów termofizycznych mas formierskich na strukturę badanego stopu silnie zależą od grubości ścianek odlewu.

EN

In this paper the mathematical relationships between chosen stereological parameters of carbide phase in high chromium 2,2%C and 22%Cr cast iron ant thermal conductivity coefficient of moulding sand λ, has been presented. It has been found that the direction of an influence of thermo physical parameters of moulding sand on the structure of tested alloy strongly depends on the cast wall thickness.

18

Wpływ grubości ścianki odlewu na morfologię węglików w stopie wysokochromowym

Bieńko G., Drotlew A., Kubicki J.

Archiwum Odlewnictwa

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2002

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R. 2, nr 4

50--55

PL

W artykule przedstawiono wyniki badań mikrostruktury wysokochromowego żeliwa białego o następującym składzie chemicznym (%mas.): 2,2%C, 22%Cr, 0,3%Si, 0,01%Al 0,028%P, 0,023%S dla różnych grubości ścianek odlewu (6, 12, 18, 24, 30mm). Na podstawie wyników badań określono wpływ grubości ścianki na morfologię fazy węglikowej badanego stopu. Do określenia parametrów stereologicznych fazy węglikowej wykorzystano program Visilog4.

EN

In the article the author has presented the results of the research on microstructure of high chromium white cast iron consisting of 2,2%C, 22%Cr, 0,3%Si, 0,01%Al 0,028%P, 0,023%S obtained for different thickness of the casting wall. An influence of wall thickness on the morphology of carbide phase has been determined. Using software Visilog4.

19

Badanie połączeń żeliwo - wtop stalowy w zbrojonych odlewach odpornych na ścieranie

Kubicki J., Kochmańska A.

Archiwum Technologii Maszyn i Automatyzacji

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2001

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Vol. 21, Nr spec

113-121

PL

W odpornych na ścieranie odlewach z żeliw wysokochromowych często zatapia się pręty sta-lowe, aby w ten sposób ułatwić późniejszy montaż. W artykule przedstawiono metody przygoto-wania powierzchni prętów stalowych przed ich zatopieniem w żeliwie, a także badania wytrzymałościowe i mikroskopowe uzyskanych połączeń. Stwierdzono, że para wodna powstająca z wilgotnych mas formierskich w czasie zalewania skrapla się na częściach stalowych i uniemożliwia uzyskanie dobrych połączeń. Po usunięciu tej wady uzyskano połączenia o zadowalającej jakości, w których najsłabszym miejscem okazał się obszar pręta stalowego znajdujący się w bezpośrednim sąsiedztwie odlewu. Późniejsza obróbka cieplna zniwelowała tę wadę. Badania mikroskopowe wykazały, że mimo małej masy odlewu następuje dyfuzja węgla z żeliwa do stali. Dyfuzji chromu na tej samej drodze nie stwierdzono.

EN

'Steel bars are often drowned into wear resistant high-chromium cast irons to facilitate thei later assembly. In this paper the methods of surface preparation of steel bars before drowning then in cast iron are presented. The author also presents mechanical testing and microscopic studies o manufactured connections. It was found that the water vapour from moist moulding sand condenses on steel parts during casting. This phenomenon makes impossible obtaining good connec-tions between steel and cast iron. Elimination of this defect enabled to manufacture the high qual-ity connections. The weakest point of this connection was the area of the steel bar in neighbour-hood of casting. The later heat treatment removed this defect. Microscopic investigations showed that despite small weight of casting the diffusion of carbon from cast iron into steel takes place. Diffusion of Cr is not observed.

20

Zbrojenie odlewów z żeliw wysokochromowych. Dobór materiałów i sposobu obróbki cieplnej

Kubicki J.

Krzepnięcie Metali i Stopów

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2000

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R. 2, nr 44

477--483

PL

W publikacji autor zajmował się doborem materiałów odpornych na ścieranie z przeznaczeniem na zbrojone odlewy do maszyn wytwarzających ceramikę budowlaną. W wyniku badań stwierdzono, że miejscem o najniższej odporności na ścieranie jest część wtopu stalowego leżąca bezpośrednio przy odlewie. Dlatego na wtopy stalowe należy dobierać stal do ulepszania cieplnego a obróbkę cieplną całej części projektować tak, aby uzyskać wysoką twardość części stalowej. Opracowane rozwiązanie zastosowano w praktyce uzyskując 10.krotny wzrost żywotności badanych części.

EN

In this paper the author has dealt with selection of wear resistant materials for reinforced castings used in machines which produce building ceramics. It has been stated that, in case of reinforced castings, the place, which shows the lowest wear resistant is the part of the steel inserted piece lying immediately close to the casting. Therefore the inserted pieces should be made of toughening steel and the heat treatment of a whole element should be designed in the way, which assure obtaining the high hardness of the steel part. The elaborated solution has been applied in practice giving ten times greater life of the part.