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S. Pietrowski and G. Gumienny

Abstract

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.

Open access

W. Wołczyński

Metallurgy and Materials 44 , 365-371 (1999). [7] J. Kloch, B. Billia, T. Okane, T. Umeda, W. Wołczyński, Experimental Verification of the Solute Redistribution in Cellular/Dendritic Solidification of the Al-3.5Li and Fe-4.34Ni Alloys, Materials Science Forum 329/330 , 31-36 (2000). [8] W. Wołczyński, J. Kloch, Mass Conservation for Micro-segregation and Solute Redistribution in Cellular/Dendritic Solidification with Back-Diffusion, Materials Science Forum 329/330 , 345-351 (2000). [9] H.D. Brody, M.C. Flemings, Solute Redistribution in Dendritic

Open access

M. Rozmus-Górnikowska and M. Blicharski

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).

Open access

A. Grajcar

-Ozgowicz E., Opiela M., Grzegorczyk B., Gołombek K. (2011). Effects of Mn and Nb on the macro- and microsegregation in high-Mn high-Al content TRIP steels. Archives of Materials Science and Engineering. 49/1 , 5-14. Bhattacharya D. (2011). Perspectives on coated advanced high strength steels for automotive applications, Proc. of the 8 th Inter. Conf. "GALVATECH'2011", Genova. 3-11. Zajac S., Schwinn V., Tacke K. H. (2005). Characterisation and quantification of complex bainitic microstructures in high and ultra

Open access

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

recalescence. Metallurgical and Materials Transactions A , 27(3), 657-669. DOI: dx.doi.org/10.1007/BF02648953. [4] Warren, J.A. & Boettinger, W.J. (1995). Prediction of dendritic growth and microsegregation patterns in a binary alloy using the phase-field method. Acta Metallurgica et Materialia. 43(2), 689-703. [5] Boettinger, W.J. & Warren, J.A. (1999). Simulation of the cell to plane front transition during directional solidification at high velocity. Journal of Crystal Growth. 200(3), 583-591. DOI: dx.doi.org/10.1016/S0022-0248(98)01063-X. [6] Braun

Open access

W. Wołczyński

Metallurgy and Materials 44 , 365-371 (1999). [7] J. Kloch, B. Billia, T. Okane, T. Umeda, W. Wołczyński, Experimental Verification of the Solute Redistribution in Cellular/Dendritic Solidification of the Al-3.5Li and Fe-4.34Ni Alloys, Materials Science Forum 329-330 , 31-36 (2000). [8] W. Wołczyński, J. Kloch, Mass Conservation for Micro-Segregation and Solute Redistribution in Cellular/Dendritic Solidification with Back-Diffusion, Materials Science Forum 329-330 , 345-351 (2000). [9] H.D. Brody, M.C. Flemings, Solute Redistribution in Dendritic

Open access

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

Abstract

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.

Open access

D. Kalisz, S. Gerasin, P. Bobrowski, P.L. Żak and T. Skowronek

Abstract

The quality of rail steel is conditioned by its high mechanic qualities, which greatly depend on the presence of undesired nonmetallic inclusions. The paper is devoted to the segregation of components, mainly sulphur, and the formation of manganese sulphide in the process of steel solidification, at the casting rate of 100 and 500 K/min. Sulphur is a steel component which disadvantageously influences its numerous parameters. The oxide-sulphide and sulphide precipitations cause cracks and lower the strength of the material. This phenomenon was modeled with the use of author’s computer program based on Matsumiya interdendritic microsegregation model. The main assumptions of this model and thermodynamic conditions of inclusion formation during casting of steel are discussed in this paper. Two cases were analyzed: in the first one the MnS was assumed to form a pure and constant compound, whereas in the other one the manganese sulfide was precipitated as a component of a liquid oxide solution, and its activity was lower than unity. The final conclusion is that chemical composition of steel is the major parameter deciding about the formation of MnS inclusions.

Open access

G. Boczkal and B. Mikułowski

Abstract

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.

Open access

J. Szajnar, A. Dulska, T. Wróbel and J. Suchoń

Abstract

In paper a method of improvement in utility properties of unalloyed cast steel casting in result of diffusion of C and Cr in process of creation of surface layer is presented. The aim of paper was determination of diffusion range of basic elements of alloyed surface layer. Moreover a quantitative analysis of carbides phase strengthens alloyed surface layer of casting was carried out. The results of studies shown that important factors of surface layer creation are maximal temperature Tmax on granular insert – cast steel boundary dependent of pouring temperature, granularity Zw of Fe-Cr-C alloy insert and thickness of casting wall gśo. On the basis of obtained results was affirmed that with increase of thickness of casting wall increases range of diffusion in solid state in Fe-Cr-C grains and in liquid state. Moreover the range of Tmax = 13001500oC favours creation of the proper alloyed surface layers on cast steel.