Wyniki wyszukiwania - Biblioteka Nauki

1

The method of production of thin-walled castings made of GX2CrNiMoN25-6-3 cast steel

100%

Nadolski M. , Stradomski G. , Zyska A.

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tom Vol. 16, No. 2

104--109

EN

The possibility of production of thin-walled castings made of GX2CrNiMoN25-6-3 cast steel was assessed for the exemplary final casting with variable wall thickness. The assessment both of the solidification process of the GX2CrNiMoN25-6-3 alloy and of the final degree of mould cavity filling was done by means of the NovaFlow&Solid program. The body of the casting with its variable wall thickness, including sections thinner than 1 mm, demanded for the appropriate production technology. There are presented the results of technological tests with respect to the application of the centrifugal casting, which confirm the adopted technology of pattern and mould production. The analyzed technology makes possible the production of casting of high surface quality, while simultaneously the yield is increased, and by the same the unit cost of production is lower as compared with the production method used thus far.

PL

W pracy ocenie poddano możliwość wykonania cienkościennych odlewów ze staliwa GX2CrNiMoCuN25-6-3 na przykładzie docelowego odlewu o zmiennej grubości ścianki. Wykonano ocenę wypełniania i krzepnięcia stopu GX2CrNiMoN25-6-3 na podstawie symulacji komputerowej wykonanej przy użyciu programu NovaFlow&Solid. Bryła odlewu o zmiennej grubości ścianki, w tym nawet poniżej jednego 1 mm, wymogła zastosowanie odpowiedniej technologii wykonania. Przedstawiono wyniki prób technologicznych odlewania odśrodkowego, potwierdzające przyjętą technologię modelu i formy. W porównaniu do dotychczas stosowanej metody wykonania, analizowana technologia umożliwia wykonywanie odlewów o wysokiej jakości powierzchni przy jednoczesnym zwiększeniu uzysku i tym samym obniżając koszty wykonania jednostkowego odlewu.

2

Physical and Numerical Modeling of Duplex Cast Steel Thin-Walled Castings

100%

Stradomski G. , Nadolski M. , Zyska A. , Kania B. , Rydz D.

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tom Vol. 64, iss. 4

1449--1456

EN

The paper, which is a summary and supplement of previous works and research, presents the results of numerical and physical modeling of the GX2CrNiMoCuN25-6-3 duplex cast steel thin-walled castings production. To obtain thin-walled castings with wall in the thinnest place even below 1 mm was used the centrifugal casting technology and gravity casting. The analyzed technology (centrifugal casting) enables making elements with high surface quality with reduced consumption of batch materials and, as a result, reducing the costs of making a unitary casting. The idea behind the production of cast steel with the use of centrifugal technology was to find a remedy for the problems associated with unsatisfactory castability of the tested alloy. The technological evaluation of the cast construction was carried out using the Nova Flow & Solid CV 4.3r8 software. Numerical simulations of crystallization and cooling were carried out for a casting without a gating system and sinkhead located in a mold in accordance with the pouring position. It was assumed that the analyzed cast will be made in the sand form with dimensions 250×250×120 mm.

3

The effect of parameters and geometry cutting edge after turning of the duplex cast steel on the maximum tool flank wear

88%

Dyl T. C.

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tom Vol. 26, No. 2

29--35

EN

It is important to shape the required properties of the surface layer in the technological process. This issue is an important problem due to the ability of the kinematic pair elements to the required reliable operation of machine parts. The latest generation devices work with increasing operational loads. This forces the search forever-newer construction materials or innovative manufacturing engineering technologies that would ensure high reliability and durability of machine components. For mechanical engineering, continue to be used on steel structures of machine parts. In the petrochemical and shipbuilding industry, stainless steels are very poplars. Those materials are used in the constructions of seawater and acid installations. Currently, a newer material with more favourable properties is two-phase stainless steel. This is the so-called duplex steel. It can be applied to pump shafts in acid or seawater solutions. Duplex cast steel is a difficult-to-cut material. It is important to determine the effect of cutting parameters on the surface quality of the shafts and wear of cutting edge. Traditional methods of finishing surface treatment of shafts are machining (turning, grinding, superfinishing). Considering the possibilities of equipping a marine power plant workshop, it would be best to use machining by turning. The paper specifies the relationship between the wear of the cutting edge and the geometrical structure of the machined surface as well as the type of tool material used and the shape of the cutting inserts.

4

The Influence of Hyperquenching Temperature on Microstructure and Mechanical Properties of Alloy Cast Steel GX2CrNiMoCuN 25-6-3-3

88%

Jurczyk P. , Wróbel T. , Baron C. , Jurczyk P. , Wróbel T. , Baron C.

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nr 1

5

Characterization of solidification and solid state transformation in duplex cast steel: thermo-calc investigation

75%

Stradomski Z. , Dyja D.

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2007

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tom Vol. 7, iss. 3

269-272

EN

The paper presents a characteristic of solidification process and changes occurring in the solid state in a duplex cast steel. Theoretical chemical composition of individual phases, its changes during solidification and cooling after solidification and also changes in volume fractions of phases versus temperature have been determined. Theoretical results of Thermo-Calc analysis have been correlated with the microstructure of as-cast cast steel as well as with analysis of chemical composition of individual phases, carried out on a scanning microscope equipped with an EDS attachment. It has been shown that at the carbon content of 0.1% the enrichment of residual liquid phase with carbon results in a peritectic reaction, changing the ferritic solidification model typical for cast steels with low carbon content. In the case of solidification grain boundary areas enrichment with carbon, chromium and molybdenum there is a possibility of carbides precipitation already in the liquid state, what increases propensity for hot cracking and reduces the quality of castings produced. A correlation between theoretical composition of ferrite, austenite and M23C6 carbides, determined based on Thermo-Calc software, and their actual composition determined based on local analyses of chemical composition carried out on a scanning microscope has been shown. The volume fractions of ferrite, austenite and carbides determined using Thermo-Calc software show a strong correlation with actual fractions of those phases in the examined alloy's structure. The chemical composition of ferrite, austenite and carbides determined using Thermo-Calc software does not show any more such strong correlation with the actual chemical composition of those phases determined based on local analyses of chemical composition carried out using a scanning microscope.

6

Surfacing 24Cr-5Ni-2.5Mo Duplex Steel Castings by TIG

75%

Kalandyk B. , Kasińska J. , Skrzypczyk A.

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nr 2

7

Odporność korozyjna dwufazowego staliwa 24Cr-5Mn-2Ni-3Mo

75%

Kalandyk B. , Starowicz M. , Zapała R.

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tom Vol. 15, iss. 4 spec.

53--56

PL

Przedmiotem badań było porównanie odporności na korozję elektrochemiczną dwóch gatunków kwasoodpornego staliwa ferrytyczno-austenitycznego (duplex): klasycznego zawierającego 24Cr-5Ni-2,5Mo-2,6Cu z nowym gatunkiem staliwa zawierającym 24Cr-5Mn-2Ni-3Mo, w którym Ni częściowo został zastąpiony przez Mn i N. Zawartość pierwiastków austenitotwórczych (Ni, Mn i N) została tak dobrana, aby udział ferrytu δ w staliwie wynosił 45÷50%. Na podstawie przeprowadzonych badań korozyjnych stwierdzono, że oba materiały ulegają samorzutnej pasywacji w 3% roztworze NaCl. Staliwo z podwyższoną zawartością Mn i N posiada znacznie wyższą wartość potencjału bezprądowego (Eo = -0,7 V), niż klasyczne staliwo duplex (Eo = -0,95V) oraz wykazuje zasadnicze różnice w gęstości prądu anodowego. Jest ono również bardziej odporne na korozję lokalną. Analiza mikrostrukturalna produktów korozji wskazuje na obecność nielicznych wżerów korozyjnych powstających głównie na wtrąceniach niemetalicznych.

EN

The aim of the studies was to compare the electrochemical corrosion resistance of the two grades of acid-resistant cast austenitic-ferritic (duplex) steel, i.e. the conventional grade containing 24Cr-5Ni-2.5Mo-2.6Cu and a cast steel grade containing 24Cr-5Mn-2Ni-3Mo, where Ni was partially replaced by a higher content of Mn and N. The content of austenite-forming elements (Ni, Mn and N) has been chosen in such a way as to keep the δ ferrite fraction in the cast steel at a level of 45 ÷ 50%. Based on the corrosion test results, it was found that both materials undergo a spontaneous passivation in the 3% NaCl solution. The cast steel with increased content of Mn and N has a much higher value of the electro less potential (Eo = -0.7 V) than the conventional cast duplex steel (Eo = -0,95V), and shows substantial differences in the anodic current density. It is also more resistant to local corrosion. Microstructural analysis of corrosion products indicates the presence of very few corrosion pits formed mainly on the non-metallic inclusions.

8

Technological Assessment of the Possibility of Making Light-section Castings of GX2CrNiMoN25-6-3 Cast Steel by the Centrifugal Casting Method

75%

Stradomski G. , Nadolski M. , Stradomski Z.

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tom Vol. 15, iss. 3

57--60

EN

The paper presents the results of investigation into the technological possibility of making light-section castings of GX2CrNiMoN25-6-3 cast steel. For making castings with a wall thickness in the thinnest place as small as below 1 mm, the centrifugal casting technology was employed. The technology under consideration enables items with high surface quality to be obtained, while providing a reduced consumption of the charge materials and, as a result, a reduction in the costs of unit casting production.

9

Ferritic-austenitic cast steel - selected problems

63%

Stradomski Z.

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2011

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tom Vol. 11, iss. 3

47-50

EN

The author has been involved in the problems occurring in the manufacture of ferritic-austenitic cast steel castings for many years. The author's remarks and investigation results reported in this article will enable potential manufacturers to determine their own technical capabilities and structural determinants related to the chemical composition of material, which are crucial to the good quality of a casting. Particular emphasis should be laid on the role of enhanced carbon content, the presence of copper, the precipitates of the [...] phase, and the nature of solidification structure in the tendency of duplex-type cast steel to cracking. It seems that in view of the pro-ecological activities undertaken, including flue gas desulphurization in coal-fired power plants, efforts should be made in steel foundries to introduce selected grades of ferritic-austenitic cast steel to production.

10

The effect of burnishing process on the change of the duplex cast steel surface properties

63%

Charchalis A. , Dyl T. , Rydz D. , Stradomski G.

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2018

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tom Vol. 39, nr 6

223--227

EN

Throughout planning of technological process of manufacturing or regenerating machine components, the method of burnishing, the machining conditions, the shape and number of burners should be selected. The choice of static pressure conditions during burnishing process is dependent on how the pressure components are applied to the workpiece surface, which can be elastic or rigid. The reliability of working machine and equipment is very important in the engineering, power, metallurgical or marine industries. For example, on a ship during a cruise, are made repairs of individual components of the ship’s machinery. Often are regenerated external cylindrical surfaces (e.g. shaft seals of seawater pumps), for this purpose can be proposed burnishing process can be proposed as a finishing, which enables to obtain the technological quality requirements of the products surface layer. The effect of technological conditions of burnishing process on the degree of relative strain hardening and surface roughness reduction ratio were presented. The burnishing process carried out for duplex cast steels series GX2CrNiMoCuN25–6–3–3. The use of duplex cast steel burnishing process is a novelty technology. The experimental investigation were obtained in the surface layer increase in hardness and the material ratio curve a convex shaped, which, taking into account the load capacity of the surface will be directly affected by its resistance to wear and corrosion. The experimental research by application of the burnishing process were made in the Laboratory of Production Engineering of the Department of Marine Maintenance. After the studies it was found that the hardness of the surface layer and the roughness of the shaft necks an important influenced by technological parameters of processing (the recommended parameters: burnishing speed vn = 70 m/min; feed rate fn = 0.2 mm/rev; depth of burnishing an = 1.0 mm; number of machining passes i = 2). The aim of applying burnishing may be, for example, the need to increase surface smoothness and dimensional accuracy of part.

PL

Celem pracy było wyznaczenie wpływu parametrów obróbki plastycznej przez nagniatanie na zmianę współczynnika zmniejszenia chropowatości powierzchni i względnego stopnia umocnienia warstwy wierzchniej staliwa typu dupleks. W artykule przedstawiono wyniki badań doświadczalnych nagniatania staliwa typu dupleks w gatunku GX2CrNiMoCuN25–6–3–3. Nagniatanie czopów wałów przeprowadzono z wykorzystaniem nagniataka krążkowego (NK-01). Po przeprowadzonych badaniach eksperymentalnych określono, że występuje wzrost stopnia umocnienia, następuje zmniejszenie chropowatości, a krzywa udziału materiałowego ma kształt wypukły, co, biorąc pod uwagę nośność powierzchni, wpływa bezpośrednio na jej odporność na zużywanie ścierne i korozyjne. Stwierdzono, że na twardość warstwy wierzchniej oraz chropowatość zewnętrznych powierzchni walcowych mają wpływ parametry technologiczne: posuw nagniatania, dosuw nagniataka, prędkość nagniatania i liczba przejść obróbkowych.

11

Model krzepnięcia wysokostopowych staliw Fe-Cr-Ni

63%

Dyja D. , Stradomski Z.

Archiwum Odlewnictwa

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2006

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tom R. 6, nr 19

81-88

PL

W pracy przedstawiono ogólne modele krzepnięcia wysokostopowych, odpornych na korozję staliw Fe-Cr-Ni ze szczególnym uwzględnieniem mechanizmu krzepnięcia ferrytyczno-austenitycznych staliw typu duplex. Na podstawie badań własnych wykazano, że zjawiska mikrosegeracji, szczególnie węgla, chromu i molibdenu do granic pierwotnego ziarna krzepnięcia, zmieniają mechanizm krzepnięcia z ferrytycznego na ferrytyczno-austenityczny, a obecność reakcji perytektycznej negatywnie wpływa na własności technologiczne, zwiększając skłonność do pękania na gorąco. Przeprowadzone w pracy badania makro i mikrostruktury oraz mikroanalizy składu chemicznego staliw w stanie surowym, o zróżnicowanej zawartości węgla, ujawniły możliwość wydzielania się węglików pierwotnych już z cieczy. Uprzywilejowane rozmieszczenie węglików w obszarach przygranicznych pierwotnego ziarna krzepnięcia w połączeniu z występującym w niższych temperaturach wydzielaniem się fazy \sigma zwiększa niebezpieczeństwo powstania pęknięć w wolno stygnących odlewach.

EN

The general solidification models of highly alloyed, corrosion resistant Fe-Cr-Ni cast steel, together with the particular consideration of ferritic-austenitic duplex cast steels were shown in the work. On the basis of personal investigations it was shown, that microsegregation especially of carbon, chromium and molybdenum to the primary solidification grain boundaries, changes the solidification mechanism from ferritic to ferritic-austenitic. The presence of peritectic transformation has a negative effect on technological properties, increasing the hot crack sensitivity . Macro and microstructure examinations and chemical composition microanalysis of the cast steel at as-cast condition with various carbon content , revealed the possibility of primary carbide precipitation from the liquid. Privileged distribution of carbides in the primary solidification grain boundaries, in connection with sigma phase precipitation occurred at the lower temperatures increases danger of cracking in low-cooling castings.

12

Nagniatanie staliwa typu dupleks w aspekcie zwiększenia twardości i zmniejszenia chropowatości powierzchni

63%

Dyl T. , Rydz D. , Stradomski G.

Zeszyty Naukowe Akademii Morskiej w Gdyni

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2017

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tom nr 100

76--86

PL

W artykule przedstawiono wyniki badań doświadczalnych nagniatania statycznego naporowego tocznego (NSNT) staliwa typu dupleks w gatunku GX2CrNiMoCuN25-6-3-3. Nagniatanie czopów wałów przeprowadzono z wykorzystaniem nagniataka krążkowego (NK-01). Po przeprowadzonych badaniach eksperymentalnych określono, że występuje wzrost stopnia umocnienia, następuje zmniejszenie chropowatości, a krzywa udziału materiałowego ma kształt wypukły, co, biorąc pod uwagę nośność powierzchni, wpływać będzie bezpośrednio na jej odporność na zużywanie ścierne i korozyjne. Po przeprowadzonych badaniach stwierdzono, że na twardość warstwy wierzchniej oraz chropowatość zewnętrznych powierzchni walcowych istotny wpływ mają parametry technologiczne obróbki: posuw nagniatania, głębokość dosuwu nagniataka, prędkość nagniatania i liczba przejść obróbkowych. Obróbkę nagniataniem staliwa typu dupleks gładkościową i umacniającą wykonano przy zadanych parametrach: posuw nagniatania fn = 0,2 mm/obr; głębokość dosuwu nagniataka an = 1,0 mm, prędkość nagniatania vn = 70 m/min i liczba przejść obróbkowych i = 2.

EN

The paper presents results of experimental studies of burnishing rolling – pressuring (BRP) cast steel grade GX2CrNiMoCuN25-6-3-3. Burnishing of the shafts neck is proposed using burnisher roller (BR–01). In experimental studies it has been stated that there is a surface layer increase in hardness, roughness reduction and the material ratio curve is convex shaped, which, taking into account the load capacity of the surface, will directly affect its resistance to wear and corrosion. After studies it was found that the hardness of the surface layer and the roughness of the shaft necks are significantly influenced by technological parameters of processing. To achieve the objectives of strengthen and smooth burnishing of cast steel duplex should be used: feed fn = 0.2 mm/rev and disk burnishing tool feed an = 1.0 mm, burnishing speed vn = 70 m/min and the passes i = 2.

13

The Cracking Mechanism of Ferritic- Austenitic Cast Steel

63%

Stradomski G.

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tom Vol. 16, iss. 4

153--156

EN

In the high-alloy, ferritic - austenitic (duplex) stainless steels high tendency to cracking, mainly hot-is induced by micro segregation processes and change of crystallization mechanism in its final stage. The article is a continuation of the problems presented in earlier papers [1-4]. In the range of high temperature cracking appear one mechanism a decohesion - intergranular however, depending on the chemical composition of the steel, various structural factors decide of the occurrence of hot cracking. The low-carbon and low-alloy cast steel casting hot cracking cause are type II sulphide, in high carbon tool cast steel secondary cementite mesh and/or ledeburite segregated at the grain solidified grains boundaries, in the case of Hadfield steel phosphorus - carbide eutectic, which carrier is iron-manganese and low solubility of phosphorus in high manganese matrix. In duplex cast steel the additional factor increasing the risk of cracking it is very "rich" chemical composition and related with it processes of precipitation of many secondary phases.

14

The Role of Carbon in the Mechanism of Ferritic-Austenitic Cast Steel Solidification

63%

Stradomski G.

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2014

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tom Vol. 14, iss. 3

83--86

EN

The paper presents the results of research on the microstructure of GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoCuN25-6-3 cast steels with a varying carbon content. The cause for undertaking the research were technological problems with hot cracking in bulk castings of duplex cast steel with a carbon content of approx. 0.06% and with 23% Cr, 8.5% Ni, 3% Mo and 2.4% Cu. The research has shown a significant effect of increased carbon content on the ferrite and austenite microstructure morphology, while exceeding the carbon content of 0.06% results in a change of the shape of primary grains from equiaxial to columnar.

15

Technologiczne problemy wytwarzania masywnych odlewów ze staliwa duplex w aspekcie optymalizacji procesu produkcyjnego

63%

Stradomski Z. , Stachura S. , Dyja D. , Zyska A.

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tom R. 5, nr 17

287--292

PL

W pracy przedstawiono problemy wykonywania masywnych, 2-3 tonowych, odlewów ze staliwa typu duplex. Badaniom poddano odlewy w stanie surowym, o zmiennej zawartości węgla. Wykazano, że nawet niewielkie różnice w jego zawartości, znacząco wpływają na tworzenie się obszarów segregacyjnych związanych z występowaniem cieczy resztkowej w czasie krzepnięcia. Obszary te charakteryzują się znaczną koncentracją węglików oraz fazy sigma i są miejscem uprzywilejowanego tworzenia się pęknięć dyskwalifikujących odlewy.

EN

Problems related with production of massive, 2-3 tone-castings of duplex cast steel have been presented in this work. Castings in the as-cast conditions, with the variable carbon content from 0,05% to 0,11% have been investigated. Using the material with the various carbon contents, the authors proved, that even small differences in their contents have significant role in segregation area, connected with occurrence of the residual liquid during solidification. These areas have the large carbides and sigma phase concentrations, they are also the privileged places for origination of the cracks, what disqualify the cast.

16

The Burnishing Process of the Duplex Cast Steel in Aspect of Improving the Tribological Properties

63%

Stradomski G. E. , Fik J. , Rydz D.

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tom Vol. 23, iss. 2

51--57

EN

Duplex cast steel it is a material with great potential. The properties of this material have contributed to its wide application in many industrial sectors, for example: oil extraction, printing, petrochemical industry, energy - flue gas desulphurization systems, seawater desalination plants, shipbuilding industry. The article presents the results of tribological tests following the static pressure roller burnishing (SPRB) process of GX2CrNiMoN22-5-3 duplex cast steel. The tests provided a basis for assessing the effect of the burnishing parameters on tribological properties of that material. The issue is important because the authors focused their research on duplex cast steels grade that are not containing copper. The article presents part of the research concerning the influence of the burnishing process on the properties of the duplex steel surface layer. Copper in duplex steels affects many areas one of them is the plastic properties. Its absence also reduces castability. Because of that it is reasonable to determine to what extent the properties of the surface layer of copper-free duplex cast steel grades can be shaped in burnishing process.

17

Influence of carbon content on the segregation processes in duplex cast steel

63%

Stradomski Z. , Dyja D.

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2007

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tom Vol. 7, iss. 1

139-142

EN

The paper aimed at determination of increased carbon content influence on segregation processes in a duplex ferritic-austenitic cast steel. The analysis of raw cast steel structure was carried out using a Zeiss Axiovert 25 optical microscope. The chemical composition of selected areas was examined using a JEOL JSM 5400 scanning microscope equipped with an EDX microanalyser and the obtained results were verified using the Thermo-Calc software. The investigations carried out have shown that the lower carbon content causes the smaller amount of the intermetallic phases precipitates undesirable in the manufacturing process, which – affecting a clear deterioration in raw cast steel impact strength – promote origination of cracks in the castings. The increased, due to segregation processes, content of carbon, chromium and molybdenum within the solidification grain boundaries promotes precipitation of carbides already in the liquid state, what increases the propensity for hot cracking. The molybdenum content, in a cast steel of increased carbon content, varies from ~4% in the centre of solidification grain to ~6.5% in its boundary areas, and the chromium content from ~28% to 32%, respectively. Small enrichment of ferrite with molybdenum and chromium in boundary areas of cast steel solidification grains containing 0.02% carbon causes higher ferrite stability and prevents its decomposition in the temperature range from 600 to 900°C, what makes that the cast steel of lower carbon content features uniform ferritic-austenitic structure in as cast state.

18

The influence of carbon and copper on the solidification process of the ferritic-austenitic cast steel

51%

Stradomska J.

|

2009

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tom Vol. 9, iss. 3

177-180

EN

Technological problems which occur during the production of castings made of ferritic-austenitic (duplex) cast steel have caused that this most modern material among corrosion-resistant cast steels is seldom produced in Poland. The main reason of arising problems is the necessity of achieving a very low carbon content (Cmax = 0.03%, according to PN-EN 10283:2004) and the occurring of hot cracking. It is impossible for our domestic foundries to achieve such a low carbon content, because it demands for out-of-furnace treatment. It should be mentioned that the standards developed by international cast steel producers admit also cast steel grades with higher carbon content than the PN-EN 10283:2004 Standard. The so far produced in Poland massive castings have exhibited higher (0,05 - 0,12) carbon content, but also the significant hot cracking susceptibility. Is the increased carbon content along with about 3% copper addition, which lowers the temperature of the end of solidification process, the reason of hot cracking of produced castings? The paper presents the results of investigation performed by DDTA and ThermoCalc analyses, as well as by microstructural examination for duplex cast iron with varying carbon content.

19

Optimization of heat treatment in aspect of production's costs reducing and improving of casting quality from duplex cast steel

51%

Dyja D. , Stradomski Z.

|

2007

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tom Vol. 7, iss. 3

39-42

EN

The paper determines possibilities of cost optimisation in the production of GX2CrNiMoCu25-6-3-3 type duplex cast steel castings through selection of appropriate solution heat treatment temperature, which value depends on the content of alloying elements. Metallographic analysis was carried out for as-cast and heat treated cast steel. Hardness and impact strength of the cast steel were determined, which were correlated with the volume fraction of phases determined by means of ImagePro computer image analyser. It has been shown that increased carbon content creates a need to use higher treatment temperatures, thereby increasing the production cost. With increasing carbon content the cast steel hardness after solution heat treatment increases, however, crack resistance decreases.

20

Comparison of Methods for Determining the Ferrite Content in Duplex Cast Steels

51%

Kaňa V. , Pernica V. , Zadera A. , Krutiš V.

|

2019

|

tom iss. 2

85--90

EN

The paper is concerned with comparing the methods for determining the ferrite content in castings from duplex stainless steels. It uses Schaeffler diagram, empirical formula based calculation, image analysis of metallographic sample, X-ray diffraction and measurement with a feritscope. The influence of wall thickness of the casting on the ferrite content was tested too. The results of the experiments show that the casting thickness of 25 or 60 mm does not have a significant effect on the measured amount of ferrite. The image analysis of metallographic sample and the measurement with the feritscope appear to be the most suitable methods. On the contrary, predictive methods, such as Schaeffler diagram or empirical formula based calculation are only indicative and cannot replace the real measurements. X-ray diffraction seems to be the least suitable measuring method. Values of ferrite content measured in such a way often deviated from the values measured by image analysis and with feritscope.