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1

Characteristics of Ledeburite in EDS Analyses of Directionally Solidified Eutectic White Cast Iron

Trepczyńska-Łent Małgorzata, Seyda J.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 4

65--71

EN

The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v=83 μm/s and v=167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite.

2

Segregation effect on solidification cracking in spot welding of the 6XXX aluminum

Ramirez Andrés, Graciano-Uribe Jonathan, Hincapie Diego, Torres Edwar

Engineering Transactions

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2020

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Vol. 68, iss. 4

417--431

EN

Solidification cracking is a critical phenomenon, especially in the welding of AA6XXX, due these alloys present a wider freezing temperature range. The amount of liquid at the end of the solidification is a dominant factor in promoting or reducing the number of cracks. This paper proposes to assess the effect of the heat input in controlling the cracking during the spot welding in AA6061-T6. Four deposit conditions, made with GTAW, were assessed, in which the cracking degree was quantified and compared with the resulting microstructure. This work confirms and explains why the heat input governs the constitutional cooling, which simultaneously controls the microsegregation amount. With low heat input, the segregation is interdendritic, and the eutectic liquid gathers within the grains, which reduces the cracking susceptibility. A high heat input promotes the higher accumulation of eutectic liquid at the grain boundaries, facilitating cracks’ formation and growth. A high concentration of eutectic liquid promotes the healing effect, reducing the formation of cracks.

3

Pattern Selection in the Eutectic Growth - Thermodynamic Interpretation

Wołczyński W.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

653--666

EN

The (Zn) – single crystal strengthened by the E = (Zn) + Zn16 Ti eutectic precipitate is subjected to directional growth by the Bridgman’s system and current analysis. Experimentally, the strengthening layers (stripes) are generated periodically in the (Zn) – single crystal as a result of the cyclical course of precipitation which accompanies the directional solidification. These layers evince diversified eutectic morphologies like irregular rods, regular lamellae, and regular rods. The L – shape rods of the Zn16 Ti – intermetallic compound appear within the first range of the growth rates when the irregular eutectic structure is formed. Next, the branched rods transform into regular rods and subsequently the regular rods into regular lamellae transitions can be recorded. The regular lamellae exist only within a certain range of growth rates. Finally, the regular rods reappear at some elevated growth rates. A new solution to the diffusion equation is provided to describe the micro-field of the solute concentration in the liquid adjacent to the front of the growing eutectic structure. The solution is based on the mass balance in the considered system. Moreover, the existence of the protrusion of the leading eutectic phase over the wetting one is required by the mass balance. The appearance of the d – protrusion in the growing eutectic is well confirmed by the experimental observations of the frozen solid/liquid interface.The mentioned solution satisfies the concept of the eutectic coupled growth according to which undercooling of the leading phase is less than undercooling of the wetting eutectic phase. Also, the Ti – solute micro-segregation / redistribution is analyzed within the matrix of the single crystal. The micro-segregation is described as a result of the solution to the adequate, newly developed differential equation. The definition for the solute redistribution is given by the subsequently / separately formulated relationship. This definition takes into account both extent -, and intensity of the solute redistribution. Finally, the entropy production is calculated for the regular lamellae -, and for the regular rods formation, respectively. The entropy production is a function of some parameters which define the eutectic phase diagram, coefficient of the diffusion in the liquid, and some capillary parameters connected with the mechanical equilibrium located at the triple point of the solid/liquid interface. Branches formation is related to the marginal stability. A new criterion is formulated and subjected to successful verification. It is: in the structural – thermodynamic competition the winner is this kind of the pattern for which minimum entropy production has a lower value.

4

Annealing effect on microstructure and chemical composition of Inconel 625 alloy

Petrzak P., Kowalski K., Rozmus-Górnikowska M., Dębowska A., Jędrusik M., Koclęga D.

Metallurgy and Foundry Engineering

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2018

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Vol. 44, no. 2

73--80

EN

Our research focused on Inconel 625 weld overlays on 16Mo3 steel boiler pipes. The investigation focused on the characterization of changes in the microstructure and chemical composition after annealing. The annealing was performed for ten hours at temperatures from 600 to 1000°C. Changes in the microstructure were observed with a scanning and transmission electron microscope (SEM and TEM). The investigation was supplemented by hardness measurements.

PL

Badania przeprowadzono na napoinach ze stopu Inconel 625 na stali kotłowej 16Mo3. Skoncentrowano się na charakterystyce mikrostruktury i składu chemicznego zmian po wyżarzaniu. Obróbkę cieplną przeprowadzono w temperaturze od 600 do 1000°C przez 10 godzin. Zmiany mikrostruktury obserwowano przy użyciu skaningowej i transmisyjnej mikroskopii elektronowej (SEM i TEM). Badania zostały uzupełnione o pomiary twardości.

5

Mikrostruktura i skład chemiczny powłok ze stopów Inconel 625 i 686 napawanych metodą CMT na stali 16Mo3

Petrzak P., Kowalski K., Rozmus-Górnikowska M.

Przegląd Spawalnictwa

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2017

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R. 89, nr 6

24--29

PL

W artykule zaprezentowano wyniki badań mikrostruktury, składu chemicznego i właściwości mechanicznych napoin ze stopów Inconel 625 i 686 (NiCr22Mo9Nb i NiCr21Mo16W) nanoszonych na rury ze stali 16Mo3. Napoiny wykonano metodą Cold Metal Transfer (CMT). Badania przeprowadzono z wykorzystaniem mikroskopii świetlnej (LM), skaningowej (SEM) i transmisyjnej (TEM). Próbki poddano jakościowej i ilościowej analizie składu chemicznego techniką EDS. Dokonano oceny mikrosegregacji pierwiastków stopowych następującej podczas krzepnięcia napoiny. Dodatkowo wykonano pomiary twardości metodą Vickersa.

EN

The paper presents results of the investigation of the microstructure, chemical composition and mechanical properties of Inconel 625 and 686 (NiCr22Mo9Nb and NiCr21Mo16W) weld overlays deposited on 16Mo3 steel. The weld overlays were made by Cold Metal Transfer (CMT) technique. Investigation were carried out using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The samples were subjected to quantitative and qualitative chemical composition analysis with use of EDS. An evaluation of microsegregation of alloy elements during solidification of the weld overlay was performed. The investigation was supplemented by the hardness measurements (Vickers method).

6

Numerical Simulation of Solidification Microstructure based on Adaptive Octree Grids

Yin Y., Li Y., Wu K., Zhou J.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 2

33--40

EN

The main work of this paper focuses on the simulation of binary alloy solidification using the phase field model and adaptive octree grids. Ni-Cu binary alloy is used as an example in this paper to do research on the numerical simulation of isothermal solidification of binary alloy. Firstly, the WBM model, numerical issues and adaptive octree grids have been explained. Secondary, the numerical simulation results of three dimensional morphology of the equiaxed grain and concentration variations are given, taking the efficiency advantage of the adaptive octree grids. The microsegregation of binary alloy has been analysed emphatically. Then, numerical simulation results of the influence of thermo-physical parameters on the growth of the equiaxed grain are also given. At last, a simulation experiment of large scale and long-time has been carried out. It is found that increases of initial temperature and initial concentration will make grain grow along certain directions and adaptive octree grids can effectively be used in simulations of microstructure.

7

Mikrostruktura i mikrosegregacja warstwy ze stopu Inconel 625 napawanej łukowo na rury kotłowe

Rozmus-Górnikowska M.

Inżynieria Materiałowa

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2015

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Vol. 36, nr 5

306--309

PL

Celem pracy była ocena mikrostruktury i mikrosegregacji warstw ze stopu Inconel 625 napawanych na rury kotłowych ze stali 16Mo3. Wykazano, że w wyniku mikrosegregacji zachodzącej podczas krzepnięcia napoin ze stopu Inconel 625 następuje znaczne wzbogacenie obszarów międzydendrytycznych, tj. obszarów między ramionami dendrytów w Nb, a mniejsze w Mo. Jaśniejsze obszary na mapach rozmieszczenia (SEM, EDS) Nb i Mo są obszarami międzydendrytycznymi wzbogaconymi w Mo i Nb, natomiast widoczne w przestrzeniach międzydendrytycznych na mapach rozmieszczenia (TEM, EDS) Nb i Mo bardzo małe, jasne obszary są mocno wzbogacone w Mo i Nb, a znacznie zubożone w Cr i Ni. W dalszych badaniach zidentyfikowano je jako wydzielenia wydzielenia fazy Lavesa i (Nb, Ti)(C, N).

EN

The aim of this work was to investigate the microstructure and microsegregation of Inconel 625 coating weld overlaid on the 16Mo3 boiler pipes. It has been shown that solidification of weld overlays brings about substantial microsegregation of Nb and Mo. The interdendritic regions, i.e. the regions between dendrite arms, are considerably with Nb, and less so with Mo. The lighter regions on the Nb and Mo distribution maps (SEM/EDS) correspond to interdendritic regions enriched with Mo and Nb. On the other hand, the very small, bright regions that are visible in the interdendritic regions on the Nb and Mo distribution maps (TEM/EDS) are considerably enriched with Mo and Nb, while they are also considerably depleted of Cr and Ni. These regions were identified as precipitates of Laves and (Nb, Ti)(C, N) phases.

8

The Brittleness Of Zn-Cu-Ti Sheet Alloys

Boczkal G., Mikułowski B.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2355--2360

EN

At temperatures below 5°C, the ductility of ZnCuTi alloy sheets is observed to suffer a drastic drop in direction transverse to the rolling direction. Studies have shown that the critical temperature at which this phenomenon occurs is strongly dependent on the alloy structure and parameters of the sheet metal production process. Quite important is also the role of micro-inhomogeneity arising in the chemical composition of the alloy matrix, directly related with the structure of intermetallic precipitates containing Cu and Ti.

PL

W blachach wykonanych z cynku stopowego ZnCuTi w temperaturach poniżej 5°C obserwowane jest zjawisko spadku plastyczności w kierunku poprzecznym do kierunku walcowania. Badania wykazały, że temperatura krytyczna dla występowania zjawiska jest silnie uzależniona od struktury stopu oraz parametrów technologicznych produkcji blach. Duże znaczenie odgrywają także mikroniejednorodności składu chemicznego osnowy, co związane jest bezpośrednio ze strukturą wydzieleń faz międzymetalicznych z udziałem Cu oraz Ti.

9

Microsegregation and Precipitates in Inconel 625 Arc Weld Overlay Coatings on Boiler Pipes

Rozmus-Górnikowska M., Blicharski M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2599--2606

EN

The aim of this work was to investigate the microsegregation and precipitates formed due to segregation in Inconel 625 arc weld overlay coatings on boiler pipes. Examination of microsegregation and precipitates were carried out by means of a scanning electron microscope (SEM) equipped with an EDS detector as well as a transmission electron microscope (TEM) equipped with a HAADF (STEM) and an EDS detectors. The presence of precipitations in the weld overlay was also confirmed with X-ray diffraction analysis (XRD) of residue in the form of powder that remained after the electrolytic dissolution of weld overlay matrix. The investigations showed that the interdendritic regions were considerably enriched during microsegregation with Nb, and less so with Mo. The distribution of Cr and Fe in the weld overlay is relatively uniform. The value of the partition coefficient k for Mo and Nb is lower than 1. Therefore, these elements segregate during solidification into the liquid and, once solidification is finished, the interdendritic regions are considerably enriched with these elements. The value of k for Cr, Ni and Fe are only slightly higher than 1. Though the Inconel 625 is a solid-solution strengthened alloy, precipitation of secondary phases occurs in weld overlays. Precipitations were identified as a Laves phase and carbonitrides (Nb, Ti)(C, N).

PL

Celem pracy była ocena segregacji dendrytycznej (mikrosegregacji) oraz identyfikacja wydzieleń w napoinach ze stopu Inconel 625 napawanych metodą CMT na rury kotłowe. Badania segregacji dendrytycznej oraz składu chemicznego wydzieleń w napoinach ze stopu Inconel 625 prowadzono za pomocą mikroskopu elektronowego skaningowego NanoSEM 450 firmy FEI wyposażonego w detektor EDS firmy EDAX oraz za pomocą mikroskopu elektronowego transmisyjnego (TEM, TECNAI GF20) wyposażonego w detektor HAADF do badań techniką skaningowo - transmisyjną STEM, jak również zintegrowany spektrometr promieniowania rentgenowskiego do analizy składu chemicznego firmy EDAX. Obecność wydzieleń została potwierdzona za pomocą rentgenowskiej analizy fazowej (XRD) cząstek proszku osadu uzyskanego w wyniku elektrolitycznego rozpuszczenia osnowy napoiny. Badania wykazały, że w wyniku mikrosegregacji zachodzącej podczas krzepnięcia napoin następuje znaczne wzbogacenie obszarów międzydendrytycznych tj. obszarów między ramionami dendrytów w Nb a mniejsze w Mo. Wartość równowagowego współczynnika rozdziału k dla Mo i Nb jest mniejsza od 1, dlatego podczas krystalizacji pierwiastki te segregują do cieczy, a zatem, po zakończeniu krystalizacji obszary międzydendrytyczne są znacznie wzbogacone w w/w pierwiastki. Pomimo, że stop Inconel 625 jest stopem umacnianym roztworowo to w napoinach występowały wydzielenia. Na podstawie wyników analizy składu chemicznego, jak również rentgenowskiej analizy fazowej wydzielenia te zidentyfikowano jako fazę Lavesa oraz (Nb, Ti)(C, N).

10

Back-Diffusion In Crystal Growth. Peritectics

Wołczyński W.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2409--2414

EN

A model for the solute micro-segregation/redistribution is delivered. The description is associated with solidification of the peritectic alloys. The peritectic transformation is treated as the phenomenon which modifies the solute redistribution profile resulting from both partitioning and back-diffusion. The relationship allowing for the amount of peritectic phase calculation is also formulated.

PL

Proponowany jest model mikrosegregacji/redystrybucji składnika stopowego. Opis ten dotyczy krystalizacji stopów perytektycznych. Transformacja perytektyczna jest traktowana jako zjawisko, które modyfikuje profil redystrybucji składnika wynikający z rozdziału i dyfuzji wstecznej. Sformułowane jest także równanie, które pozwala wyznaczyć ilość fazy perytektycznej.

11

Back-Diffusion In Crystal Growth. Eutectics

Wołczyński W.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2403--2407

EN

Solute segregation/redistribution model for some eutectic alloys is presented. The differential equation for the solute micro-segregation during solidification accompanied by the back-diffusion is formulated. The solution to this equation results in the definitions of: solidification path, solid/liquid (s/l) interface path and redistribution path. An equation for the estimation of the amount of equilibrium and non-equilibrium precipitates is also delivered. It is proved that the current model is universal one. Thus, the model reduces perfectly, mathematically to both description of diffusion-less solidification and model of equilibrium solidification.

PL

Przedstawiono model segregacji/redystrybucji składnika dla stopów eutektycznych. Sformułowano równanie różniczkowe dla mikrosegregacji składnika podczas krystalizacji, której towarzyszy dyfuzja wsteczna. Rozwiązanie tego równania pozwoliło na zdefiniowanie ścieżek: krystalizacji, frontów krystalizacji i redystrybucji. Sformułowano równanie dla oceny ilości wydzieleń równowagowych i nierównowagowych. Pokazano, że model jest uniwersalny. Dlatego, redukuje się perfekcyjnie, matematycznie do opisu krystalizacji bez dyfuzji a także do modelu krystalizacji równowagowej.

12

Badania mikrostruktury i mikrosegregacji składu chemicznego warstw ze stopu Inconel 625 napawanych techniką CMT na podłoże ze stali 16Mo3

Rozmus-Górnikowska M.

Przegląd Spawalnictwa

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2014

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R. 86, nr 12

4--8

PL

Celem pracy była ocena mikrostruktury i składu chemicznego napoin ze stopu Inconel 625 napawanych metodą CMT na podłoże ze stali 16Mo3 oraz segregacji dendrytycznej (mikrosegregacji) pierwiastków stopowych następującej podczas krzepnięcia napoiny. Badania prowadzono za pomocą mikroskopu świetlnego Axio Imager MAT. M1m firmy Carl Zeiss oraz skaningowych mikroskopów elektronowych: mikroskopu NanoSEM 450 firmy FEI wyposażonego w detektor EDS firmy EDAX oraz mikroskopu Hitachi S-3500N wyposażonego w detektor EDS firmy Noran. Wykazano, że w wyniku mikrosegregacji zachodzącej w trakcie krzepnięcia napoin rdzenie dendrytów bogatsze są w Ni, Fe i Cr, natomiast obszary międzydendrytyczne w Mo i Nb. Podczas krzepnięcia najsilniej segreguje niob, w mniejszym stopniu molibden, natomiast najmniej segreguje chrom. Pomimo, że Inconel 625 jest stopem umacnianym roztworowo to w przestrzeniach międzydendrytycznych napoin tworzą się fazy bogate w Nb i Mo.

EN

The aim of this work was to investigate the microstructure and chemical composition of Inconel 625 coatings on a 16Mo3 steel overlaid by the CMT method as well as microsegregation of alloying elements during solidification of weld overlay. The investigations were carried out with an Axio Imager MAT. M1m light microscope (LM) manufactured by the Carl Zeiss company and with a FEI NanoSEM 450 and Hitachi S-3500N scanning electron microscopies (SEM). The investigation showed that microsegregation occurring during the weld overlay solidification makes the dendrite cores to be richer in Ni, Fe and Cr while the interdendritic areas in Mo and Nb. Niobium shows the strongest tendency to segregation during solidification; molybdenum tends to segregate less and chromium has the lowest tendency to segregation. Although Inconel 625 is a solid solution strengthened alloy, Nb and Mo-rich phases are formed in the between dendrite arms of weld overlays.

13

Krystalizacja dendrytyczna ze stanu ciekłego. Cz. 2

Wołczyński W.

LAB Laboratoria, Aparatura, Badania

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2014

|

R. 19, nr 6

6--15

14

Krystalizacja dendrytyczna ze stanu ciekłego. Cz. 1

Wołczyński W.

LAB Laboratoria, Aparatura, Badania

|

2014

|

R. 19, nr 5

6--13

15

Microstructure and Microsegregation of an Inconel 625 Weld Overlay Produced on Steel Pipes by the Cold Metal Transfer Technique

Rozmus-Górnikowska M., Cieniek Ł., Blicharski M., Kusiński J.

Archives of Metallurgy and Materials

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2014

|

Vol. 59, iss. 3

1081--1084

EN

The aim of this work was to investigate the development of microstructure and variations in chemical composition in commercial Inconel 625 coatings on a ferritic-pearlitic steel overlaid by the CMT method. The investigation showed that microsegregation occurring during the weld overlay solidification makes the dendrite cores to be richer in Ni, Fe and Cr and in the between dendrite arms in Mo and Nb. Niobium shows the strongest tendency to segregation during solidification; molybdenum tends to segregate less and chromium has the lowest tendency to segregation. Although Inconel 625 is a solid solution strengthened alloy, Nb and Mo-rich phases are formed in the between dendrite arms of weld overlays.

PL

Celem pracy była ocena mikrostruktury i składu chemicznego powłok napawanych metodą CMT na podłoże ze stali ferrytyczno-perlitycznej, jak również ocena mikrosegregacji pierwiastków stopowych następująca podczas krystalizacji napoiny. Badania wykazały, że w wyniku mikrosegregacji zachodzącej w trakcie krystalizacji napoin rdzenie dendrytów bogatsze są w Ni, Fe i Cr, natomiast obszary międzydendrytyczne w Mo i Nb. Podczas krystalizacji najsilniej segreguje niob, w mniejszym stopniu molibden, natomiast najmniej segreguje chrom. Pomimo, że Inconel 625 jest stopem umacnianym roztworowo, to w przestrzeniach międzydendrytycznych napoin tworzą się fazy bogate w Nb i Mo.

16

Segregation behaviour of third generation advanced high-strength Mn-Al steels

Grajcar A.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 2

123-128

EN

The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS) used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

17

Microsegregation in nodular cast iron with carbides

Pietrowski S., Gumienny G.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 4

127-134

EN

In this paper results of microsegregation in the newly developed nodular cast iron with carbides are presented. To investigate the pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen. The distribution of linear elements on the eutectic cell radius was examined. To investigate the microsegregation pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen. The linear distribution of elements on the eutectic cell radius was examined. Testing of the chemical composition of cast iron metal matrix components, including carbides were carried out. The change of graphitizing and anti-graphitizing element concentrations within eutectic cell was determined. It was found, that in cast iron containing Mo carbides crystallizing after austenite + graphite eutectic are Si enriched.

18

Effects of Mn and Nb on the macro- and microsegregation in high-Mn high-Al TRIP steels

Grajcar A., Kalinowska-Ozgowicz E., Opiela M., Grzegorczyk B., Gołombek K.

Archives of Materials Science and Engineering

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2011

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Vol. 49, nr 1

5-14

EN

Purpose: The aim of the paper is to determine the effects of Mn and Nb on the macro- and microsegregation of new-developed (3-5)Mn 1.5Al TRIP steels in the as-cast state and after hot forging. Design/methodology/approach: To assess possible macro- and microsegregation the chemical composition was investigated in the macro scale by OES and by the use of EDS in microregions. To reveal the macrostructure the ingots were etched by Oberhoffer’s reagent. The chemical composition along a diameter of the ingots was tested as well as in different regions of the plastically deformed flats. Metallographic investigations were carried out using optical (OM) and scanning electron microscopy (SEM). Findings: The Mn and Nb contents have significant effects on the obtained bainitic-martensitic structures and the morphology of retained austenite. The tendency to macrosegregation of Mn and Al between middle and external parts of the as-cast ingots and hot forged flats was detected. The Nb micoalloying results in the overall refinement of obtained microstructures and reduces the identified segregation of Al and Mn. A little microsegregation of these alloying elements between structural constituents was also detected. Research limitations/implications: Further investigations to describe in detail the identified structural constituents and the tendency of alloying elements to segregation in the thermomechanically rolled sheets are in progress. Practical implications: The knowledge of the macro- and microsegregation of Mn and Al in the TRIP steels with a high fraction of retained austenite is of primary importance for the manufacturing paths of these multiphase structure steels. Originality/value: A problem of segregation of Al and Mn in advanced high strength steels with and without Nb microaddition was described and interesting types of bainitic structures were identified.

19

Interplay between temperature gradients field and C → E transformation in solidifying rolls

Wołczyński W., Guzik E., Kania B., Wajda W.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 4

254-260

EN

At first step of simulation a temperature field for solidifying cast steel and cast iron roll has been performed. The calculation does not take into account the convection in the liquid since convection has no influence on the proposed model for the localization of the C → E (columnar to equiaxed grains) transformation. However, it allows to study the dynamics of temperature field temporal behavior in the middle of a mould. It is postulated that for the C → E transition a full accumulation of the heat in the mould has been observed (plateau at the T(t) curve). The temporal range of plateau existence corresponds to the incubation time for the full equiaxed grains formation. At the second step of simulation temporal behavior of the temperature gradient field has been studied. Three ranges within temperature gradients field have been distinguished for the operating point situated at the middle of mould: a/ for the formation of columnar grains zone, ([...] and high temperature gradient [...]), b/ for incubation of the liquid to the C → E transformation, ([...] no temperature gradient changes [...]), c/ for equiaxed grains growth, ([...] and moderate temperature gradient [...]). T - temperature, r - roll radius. It is evident that the heat transfer across the mould decides on the temporal appearance of incubation during which the solidification is significantly arrested and competition between columnar and equiaxed growth occurs. Moreover solidification with positive temperature gradient transforms into solidification with negative temperature gradient (locally) after the incubation. A simulation has been performed for the cast steel and cast iron rolls solidifying as in industry condition. Since the incubation divides the roll into to parts (first with columnar structure, second with equiaxed structure) some experiments dealing with solidification have been made in laboratory scale. Finally, observations of the macrosegregation or microsegregation and phase or structure appearance in the cast iron ingot / roll (made in laboratory) has also been done in order to confront them with theoretical predictions. An equation for macrosegregation identification is suggested. Additionally, a new equation for redistribution studied across a given grain and its surrounding (precipitates) is also delivered. The role of the back-diffusion parameter is emphasized as a factor responsible for homogenization of the massive roll ingots.

20

Kontrola wydzieleń siarczkowych i azotkowych w produkcji blachy transformatorowej o zorientowanym ziarnie

Wypartowicz J., Podorska D.

Hutnik, Wiadomości Hutnicze

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2004

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Vol. 71, nr 6

259-264

PL

Ze względ na decydującą rolę cząstek drugiej fazy w produkcji krzemowej blachy transformatorowej o zorientowanym ziarnie, kontrola ich wielkości, rozmieszczenia i składu chemicznego jest bardzo ważna dla jakości produktu. Artykuł dyskutuje warunki termodynamiczne tworzenia wydzieleń dwóch głównych substancji: MnS i AIN. omawia metody opisu matematycznego procesów: wydzielania cząstek z ciekłej stali podczas jej krzepnięcia, redystrybucji cząstek podczas przemiany oraz wzrostu lub rozpuszczania w stali w stanie stałym.

EN

Due to the vital role of second phase particles in production of grain oriented silicon transformer steel, the control oftheir size, distribution and chemical composition is of great importance for product quality. Present article discusses thermodynamic conditions of formation of precipitates of two basic substances: MnS and AIN. The methods of mathematical modelling of processes: particles precipitation from liquid steel during soldification particles redistribution during b - y phase transition and coarsening or dissolution in solid steel are described.