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M. S. Soiński, A. Jakubus and K. Skurka

Engineering and Applied Physics of Częstochowa University of Technology. (in Polish) [19] Polish Standard PN-EN ISO 945-1: Microstructure of cast irons. Part 1: Graphite classification by visual analysis. [20] Soiński, M.S. (1986) Application of Shape Measurement of Graphite Precipitates in Cast Iron in Optimising the Spheroidizing Process. Acta Stereologica. 5, (2), 311-317. [21] Cybo, J. Jura, S. (1995). Functional description of isometric structures in quantitative metallography. Gliwice: Ed. of Silesian University of

Open access

M. Pawlyta, K. Labisz and K. Matus

Abstract

Aluminium recycling is cost-effective and beneficial for the environment. It is expected that this trend will continue in the future, and even will steadily increase. The consequence of the use of recycled materials is variable and difficult to predict chemical composition. This causes a significant reduction in the production process, since the properties of produced alloy are determined by the microstructure and the presence of precipitates of other phases. For this reason, the type and order of formation of precipitates were systematically investigated in recent decades. These studies involved, however, only the main systems (Al-Cu, Al-Mg-Si, Al-Cu-Mg, Al-Mg-Si-Cu), while more complex systems were not analysed. Even trace amounts of additional elements can significantly affect the alloy microstructure and composition of precipitates formed. This fact is particularly important in the case of new technologies such as laser surface treatment. As a result of extremely high temperature and temperature changes after the laser remelting large amount of precipitates are observed. Precipitates are nanometric in size and have different morphology and chemical composition. A full understanding of the processes that occur during the laser remelting requires their precise but also time effectively phase identification, which due to the diversity and nanometric size, is a major research challenge. This work presents the methodology of identification of nanometer phase precipitates in the alloy AlSi9Cu, based on the simultaneous TEM imaging and chemical composition analysis using the dispersion spectroscopy using the characteristic X-ray. Verification is performed by comparing the simulation unit cell of the identified phase with the experimental high-resolution image.

Open access

A.W. Bydałek, K. Najman, A. Kula, S. Biernat, L. Błaż and W. Wołczyński

Abstract

Trial series of cast alloy MO59 obtained from qualified scrap was investigated. SEM and TEM of resulting precipitates were conducted. The SEM analysis demonstrated the dependence of silicon, phosphorus, iron, chromium and nickel in the composition of the so-called hard precipitates. TEM analysis showed the formation of phase AlFeSi and AlCr. Made studies have shown the important role of the composition of the batch melts brass CuZn39Pb2 type. The analysis of SEM and TEM resulting precipitates pointed to the formation of various forms of divisions, only one of which was described in the literature character of the so-called hard inclusions. The SEM studies demonstrated the dependence of the occurrence of inclusions rich in silicon, phosphorus, iron, chromium and nickel. In contrast, additional TEM analysis indicated the formation of AlFeSi phase type and AlCr. The results of the analyses referred to the structure of the batch. Due to the difficulty of obtaining recycled materials that do not contain these elements necessary to carry out further analyzes in the direction of defining the role of phosphorus in the formation of the so-called hard inclusions.

Open access

A. Zieliński, M. Miczka and G. Golański

Abstract

The results of investigations on the microstructure of T23 and T24 low-alloy steels as well as P91 and P92 high-chromium steels in the as-received condition and after 70.000 h annealing at 550-650°C are presented. The quantitative analysis of the existing precipitates was performed for representative images of microstructure. The statistical analysis of collected data allowed the parameters of a selected theoretical statistical distribution to be estimated. A forecast of average precipitate diameter and standard deviation of such a distribution for the time of 100,000 hours at 550 and 600°C for T23 and T24 steels and at 600 and 650°C for P91 and P92 steels was calculated. The obtained results of investigations have made it possible to compare changes in the microstructure of various steel grades due to long-term impact of elevated temperature. They have also confirmed the possibility of using, in evaluating the degradation degree of materials in use, the forecasting methods that derive from mathematical statistics, in particular the theory of stochastic processes and forecast by analogy methods. The presented approach allows the development of a forecast of precipitate diameter probability density under the microstructure instability conditions for selected steel grades. The assessment of material condition that takes into consideration, but is not limited to, the precipitate diameter measurement is useful as an assessment component in estimating the time of safe service of power unit elements working under creep conditions.

Open access

G. Boczkal

Abstract

Some structure observations for the Zn-Ti0.2-Cu0.15 single crystal obtained by the Bridgman method are presented. The structure contains (Zn) - phase with inclusions of Zn16Ti inter-metallic compound. The Zn16Ti intermetallic compound is localized within the eutectic precipitates. A morphology of the Zn16Ti compound varies according to the solidification condition imposed during the single crystal growth. The block, great size particles are a characteristic element for the alloy which composition is situated nearly the eutectic point in the phase diagram. These particles were not observed previously in the hypoeutectic Zn-Ti alloys. Mechanical properties of the obtained single crystals are also investigated. Critical resolved shear stress (CRSS) during deformation in a basal slip system (0001)<11-20>is determined. The changes of the CRSS for the Zn-Ti0.2-Cu0.15 single crystals within the range of temperatures from 200K to 370K are presented. The obtained data are compared with previously investigated results for the (Zn) single crystals containing lower (hypoeutectic) titanium addition

Open access

W. Wołczyński

-segregation in Cellular Solidification, Metallurgical Transactions 25A , 2295-2301 (1994). [21] T. Himemiya, T. Umeda, Solute Redistribution Model of Dendritic Solidification Considering Diffusion in both the Liquid and Solid Phases. ISIJ International 38 , 730-738 (1998). [22] W. Wołczyński, J. Kloch, R. Ebner, W. Krajewski, The Use of Equilibrium Phase Diagram for the Calculation of Non-Equilibrium Precipitates in Dendritic Solidification. Validation, Calphad 25 , 391-400 (2002). [23] W. Wołczyński, W. Krajewski, R. Ebner, J. Kloch, The Use of

Open access

D. Kalisz, P.L. Żak, T. Tokarski, Ł. Wzorek, J. S. Suchy, M. Kiczor and W. Cieślak

The authors own computer software, based on the Ueshima mathematical model with taking into account the back diffusion, determined from the Wołczyński equation, was developed for simulation calculations. The applied calculation procedure allowed to determine the chemical composition of the non-metallic phase in steel deoxidised by means of Mn, Si and Al, at the given cooling rate. The calculation results were confirmed by the analysis of samples taken from the determined areas of the cast ingot. This indicates that the developed computer software can be applied for designing the steel casting process of the strictly determined chemical composition and for obtaining the required non-metallic precipitates.

Open access

K. Watanabe, K. Matsuda, S. Ikeno, T. Yoshida and S. Murakami

Abstract

Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2at.% and the same as, respectively. Ag or Cu added alloy showed higher maximum hardness than base alloy. The particle shape and rod shape precipitates were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased higher than that of base alloy.

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

M. Soiński

-170. Soiński M. S., Grzesiak K. (2004). Investigations concerning production of hypoeutectic low-aluminium cast iron with compact graphite. Archives of Foundry. 4 (11), 184-189. Soiński M. S., Susek P, Hübner K. et al. (2008). The low-aluminium cast iron of reduced silicon content treated with cerium mischmetal. Archives of Foundry Engineernig. 8 (2), 123-128. Soiński M. S. (1986). Application of shape measurement of graphite precipitates in cast iron in optimising the spheroidizing process. Acta Stereologica. 5 (2