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1
Content available The Burnishing Process of the Duplex Cast Steel in Aspect of Improving the Tribological Properties
Stradomski G. E., Fik Joanna, Rydz Dariusz
Archives of Foundry Engineering
|
2023
|
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.
2
Content available The Influence of Hyperquenching Temperature on Microstructure and Mechanical Properties of Alloy Cast Steel GX2CrNiMoCuN 25-6-3-3
Jurczyk P., Wróbel T., Baron C.
Archives of Metallurgy and Materials
|
2021
|
Vol. 66, iss. 1
73--80
EN
The paper presents the research results concerning the chromium-nickel-molybdenum duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade. The aim of studies was the description of the influence of hyperquenching temperature Tp i.e. 1100, 1125 and 1150°C on microstructure and mainly mechanical properties i.e. tensile strength UTS, yield strength YS, hardness HB, elongation EL and impact energy KV of duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade. The range of studies included ten melts which were conducted in foundry GZUT S.A. Based on the obtained results was confirmed that application of hyperquenching process guarantees the elimination of brittle s phase in the microstructure of studied duplex cast steel. Moreover on the basis of conducted statistical analysis of the researches results is concluded that with the decrease in hyperquenching temperature increases ductility and amount of austenite, while decreases strength and amount of ferrite in studied duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade.
3
Content available The effect of parameters and geometry cutting edge after turning of the duplex cast steel on the maximum tool flank wear
Dyl Tomasz Cyryl
Journal of KONES
|
2019
|
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
Content available Physical and Numerical Modeling of Duplex Cast Steel Thin-Walled Castings
Stradomski G., Nadolski M., Zyska A., Kania B., Rydz D.
Archives of Metallurgy and Materials
|
2019
|
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.
5
Content available Comparison of Methods for Determining the Ferrite Content in Duplex Cast Steels
Kaňa V., Pernica V., Zadera A., Krutiš V.
Archives of Foundry Engineering
|
2019
|
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.
6
Content available Kształtowanie warstwy wierzchniej staliwa typu dupleks poprzez toczenie
Dyl T.
Zeszyty Naukowe Akademii Morskiej w Gdyni
|
2018
|
nr 105
41--52
PL
W pracy przedstawiono wyniki badań własnych toczenia staliwa typu dupleks w gatunku GX2CrNiMoCuN25-6-3-3. Celem badań było określenie geometrii ostrza i para­metrów technologicznych skrawania sprzyjających uzyskaniu chropowatości, będących w zakresie obróbki bardzo dokładnej, co pozwoli na osiągnięcie odpowiedniej jakości technologicznej powierzchni przedmiotu obrabianego. Po dokonanych badaniach ekspery­men­tal­nych ustalono występowanie zmniejszenia chropowatości przy zastosowaniu odpo­wiednich płytek skrawających. Obróbkę toczeniem staliwa typu dupleks zrealizowano przy zadanych parametrach technologicznych: posuw f = 0,1–0,2 mm/obr; głębokość skrawania ap = 0,5 mm, prędkość skrawania vc = 50–100 m/min. Toczenie wykończeniowe przepro­wadzono na tokarce uniwersalnej CDS 500x1000 dla różnych geometrii wymiennych płytek wieloostrzowych typu CCMT z węglików spiekanych pokrywanych powłokami CVD.
EN
The paper presents results of experimental studies of turning cast steel grade GX2CrNiMoCuN25-6-3-3. The aim of the research was to determine the geometry of the cutting edge and the technological parameters of cutting that are conducive to obtaining the roughness in the field of very accurate machining. It can achieve the appropriate technological quality of the workpiece surface. After experimental studies it was determined that there is a reduction of roughness using suitable inserts. Turning were made for the duplex cast steel. The technological parameters of machining process were used: feed rate f = 0.1–0.2 mm/rev, depth of cut ap = 0.5 mm, cutting speed vc = 50–100 m/min. Longitudinal machining was made using universal lathe CDS 500 ´ 1000 equipped with CCMT carbide tipped inserts with CVD coatings.
7
Content available The influence of the geometry of the cutting edge and machining parameters of duplex cast steel after turning
Dyl T. C.
Journal of KONES
|
2018
|
Vol. 25, No. 4
75--81
EN
The development and research activity is connected to the production of newer and more functional products. Innovative processes are being developed and applied; services and projects are delivered. Products are work items that should be initially designed, then manufactured and finally sold and utilized. Examples of products may be airplanes, ships, cars, machine tools, gears, crankshafts, drive shaft, tubes as well as gasoline, electricity and gas, etc. The product has to meet the expectations of the future use. It is characterized by a set of functional features. In the case of machines and their capabilities and performance, for example, durability, reliability, resulting from the characteristics represented by the structural units forming the structure. The formation of the desired features of the surface layer in the technological process is an important problem due to the ability of the elements of kinematic pairs to fulfil the function as long as possible foreseen for them. The article presents results of experimental studies of turning cast steel grade GX2CrNiMoCuN25-6-3-3. The aim of the research was to determine the geometry of the cutting edge and the technological parameters of cutting that are conducive to obtaining the roughness in the field of very accurate machining. It can achieve the appropriate technological quality of the workpiece surface. After these experimental studies was determined that there is a reduction roughness using suitable inserts. Turning was made for the duplex cast steel. The technological parameters of machining process were used: feed rate f = 0.1-0.2 mm/rev, depth of cut ap = 0.5 mm, cutting speed vc = 50-100 m/min. Turning was made using universal lathe CDS 500x1000 equipped with CCMT carbide tipped inserts.
8
The effect of burnishing process on the change of the duplex cast steel surface properties
Charchalis A., Dyl T., Rydz D., Stradomski G.
Inżynieria Materiałowa
|
2018
|
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.
9
Content available Surfacing 24Cr-5Ni-2.5Mo Duplex Steel Castings by TIG
Kasinska J., Skrzypczyk A., Kalandyk B.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 2
15--20
EN
This article discusses the influence of Tungsten Inert Gas (TIG) surfacing of duplex cast steel on its hardness and structure. The samples of 24Cr-5Ni-2.5Mo ferritic-austenitic cast steel were subjected to single-overlay processes with the use of solid wire having the chemical composition similar to that of the duplex cast steel. As a result of the surfacing, the welds were obtained that had no welding imperfections with a smooth transition to the base material. In the test without the heat treatment, directly below the fusion line, we observe a ferrite band with a width of approximately 200 μm without visible austenite areas. Some of the samples were then solution treated (1060°C). Both variants, without and after solution heat treatment, were subjected to testing. Significant changes in the microstructure of the joint were observed after the heat treatment process (heat affected zone and weld microstructure changes). In both areas, an increase in the austenite volume fraction after solution heat treatment was observed. Changes in the microhardness of the ferrite in the HAZ area directly below the fusion line were also observed.
10
Content available Nagniatanie staliwa typu dupleks w aspekcie zwiększenia twardości i zmniejszenia chropowatości powierzchni
Dyl T., Rydz D., Stradomski G.
Zeszyty Naukowe Akademii Morskiej w Gdyni
|
2017
|
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.
11
Content available The Analysis of AISI A3 Type Ferritic-Austenitic Cast Steel Crystallization Mechanism
Stradomski G.
Archives of Foundry Engineering
|
2017
|
Vol. 17, iss. 3
229--233
EN
High-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel. The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich chemical composition and phenomena occurring during crystallization, must be known to the technologists. The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative analysis.
12
Content available remote The method of production of thin-walled castings made of GX2CrNiMoN25-6-3 cast steel
Nadolski M., Stradomski G., Zyska A.
Computer Methods in Materials Science
|
2016
|
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.
13
Content available The Cracking Mechanism of Ferritic- Austenitic Cast Steel
Stradomski G.
Archives of Foundry Engineering
|
2016
|
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
Content available remote Naprawa odlewów staliwnych typu duplex GX2CrNiMoCu25-6-3-3 metodą MAG drutem proszkowym
Żuk M.
Przegląd Spawalnictwa
|
2015
|
R. 87, nr 5
9--14
PL
W artykule opisano wpływ spawania naprawczego odlewów staliwnych na własności i strukturę obszarów napawanych. Badaniom poddano odlewy ze staliwa typu duplex GX2CrNiMoCu25-6-3-3, w których wykonano symulowane wady z wykorzystaniem żłobienia plazmowego, żłobienia elektrodą otuloną ChamferTrode 03 oraz żłobienia elektropowietrznego elektrodą grafitową o średnicy 6 mm. Spawanie naprawcze przeprowadzono metodą MAG drutem proszkowym Avesta Sheffield FCW 2205-H o średnicy 1,2 mm w osłonie mieszanki gazowej Ar+CO2 prądem pulsacyjnym. Obszary napawane zostały poddane badaniom wizualnym, badaniom makro, mikroskopowym, pomiarowi twardości oraz ocenie zgodności barwy po napawaniu. Przeprowadzone badania wykazały zachowanie struktury dwufazowej w obrębie SWC oraz w obszarze linii wtopienia, co może wskazywać na małe wymieszanie się spoiwa z materiałem rodzimym. W obszarach napawanych nie doszło do znacznego rozrostu ziarna. Proces spawania naprawczego nie spowodował znacznego utwardzenia w obszarze napoiny i SWC. Barwa napoin naprawczych nie wykazała znacznych różnić w stosunku do materiału rodzimego, co jest ważne podczas prowadzenia prac naprawczych odlewów staliwnych.
EN
The article describes the impact of the repair castings on the properties and structure of the deposited areas. The tests were steel castings GX2CrNiMoCu25-6-3-3 duplex in which simulated defects were made using plasma gouging, gouging coated electrode ChamferTrode 03 and electro-air gouging graphite electrode with a diameter of 6 mm. Repair welding was performed by MAG cored Avesta Sheffield FCW 2205-H with a diameter of 1,2 mm in the cover gas mixture Ar + CO2 pulsed current. Welded areas were visually tasted, tested macro, microscopic, measurement of hardness and color conformity assessment after welding. The study showed the behavior of the twophase structure within the SWC and in the fusion line, which may indicate a small mixing the binder with the parent material. In areas of the deposited there was no significant grain growth. Repair welding process did not cause a significant hardening in the weld and HAZ. The color of repair welds showed no significant differ with respect to the parent material, which is important when carrying out repair work steel castings.
15
Content available The Microstructure of Thin-walled GX2CrNiMoN25-6-3 Cast Steel Made by Centrifugal Casting
Stradomski G., Nadolski M., Stradomski Z.
Archives of Foundry Engineering
|
2015
|
Vol. 15, iss. 3 spec.
77--82
EN
The paper presents the results of investigation into the technological possibility of making light-section castings of GX2CrNiMoN25-6-3 cast steel. Due the fact that the GX2CrNiMoN25-6-3 duplex cast steel has a complex microstructure authors of this paper took on its analysis. For making castings with a wall thickness in the thinnest place as small as below 1 mm, the centrifugal casting technology, as it was presented in the paper [1], is one of the most effective technology. In the paper was made the analysis of four different parameters of the casting process and different parameters of heat treatment.
16
Content available Technological Assessment of the Possibility of Making Light-section Castings of GX2CrNiMoN25-6-3 Cast Steel by the Centrifugal Casting Method
Stradomski G., Nadolski M., Stradomski Z.
Archives of Foundry Engineering
|
2015
|
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.
17
Content available Odporność korozyjna dwufazowego staliwa 24Cr-5Mn-2Ni-3Mo
Kalandyk B., Starowicz M., Zapała R.
Archives of Foundry Engineering
|
2015
|
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.
18
Content available remote The change of solidification mechanism of ferritic-austenitic cast steel
Stradomski G., Stradomski Z., Denis-Brewczyńska D.
Journal of Achievements in Materials and Manufacturing Engineering
|
2014
|
Vol. 63, nr 2
58--64
EN
Purpose: The paper presents the results of research on the microstructure changes of two grade of duplex cast steels with a varying carbon, with and without addition of copper. Design/methodology/approach: The addition of copper have a significant effect on the microstructure of analyzed cast steels. The changes in the mechanism of solidification was also observed during numerical simulation made in the FactSage softwares. Findings: 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%. Practical implications: 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. Originality/value: Among the steel and cast steel resistant to corrosion most modern and dynamically developing group are ferritic-austenitic alloys, commonly known as duplex. Higher than austenitic steels, mechanical properties and good corrosion resistance in both overall and pitting make duplex steels irreplaceable material in the petrochemical industry, power, pulp and paper, food.
19
Content available Wytop staliwa dwufazowego sposobem odzyskowym
Bartocha D.
Archives of Foundry Engineering
|
2014
|
Vol. 14, iss. 3 spec.
3--8
PL
W pracy przedstawiono wyniki próbnych wytopów staliwa GX2CrNiMoCuN25-6-3-3 przeprowadzonych w otwartym laboratoryjnym piecu indukcyjnym sposobem odzyskowym. Wytopy polegały na przetopieniu złomu staliwa duplex, a zabiegi ograniczono tylko do końcowego odtlenienia. W ramach każdego wytopu wykonane zostały odlewy próbne schodkowe. Przedstawiono wyniki badań składu chemicznego i określono jego zmiany w różnym stadium wytopu. Na podstawie badań mikrostruktury i symulacji krzepnięcia odlewów próbnych określono wpływ szybkości stygnięcia na strukturę badanego staliwa.
EN
In the article the results of trial melts of cast steel grade GX2CrNiMoCuN25-6-3-3 conducted in an open laboratory inductive furnace with regenerative method are presented. Melts consisted on remelting scrap of duplex cast steel, and metallurgical treatment is limited only to the final deoxidation. Within each melts step-test castings are made. The results of chemical composition analysis are presented and it changes in the various stages of melting have been determined. On the basis of microstructure analysis and simulation of casting solidification, the effect of cooling rate on the structure of the tested cast steel has been estimated.
20
Content available The Role of Carbon in the Mechanism of Ferritic-Austenitic Cast Steel Solidification
Stradomski G.
Archives of Foundry Engineering
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2014
|
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.
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