Polish Institute for Ferrous Metallurgy

Gliwice, Poland

Polish Institute for Ferrous Metallurgy

Gliwice, Poland

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Zawisza B.,University of Silesia | Skorek R.,University of Silesia | Stankiewicz G.,Polish Institute for Ferrous Metallurgy | Sitko R.,University of Silesia
Talanta | Year: 2012

The preconcentration of trace elements on multiwalled carbon nanotubes (MWCNTs) followed by a wavelength-dispersive X-ray fluorescence analysis (WDXRF) has been investigated. The proposed preconcentration procedure is based on the sorption of trace elements on MWCNTs dispersed in analyzed solution. After sorption, the MWCNTs with the metal ions were collected onto the filter, and then the preconcentrated elements were determined directly by WDXRF. The preconcentration method was optimized, and in consequence, in order to obtain satisfactory recoveries using 100 mL of samples, the sorption process was performed with 1 mg of MWCNTs within 5 min. Some conditions of the preconcentration process such as the pH of analyte solution, amounts of MWCNTs, the volume of the sample, the contact time between analytes and MWCNTs (stirring time), and the effects of foreign metals are discussed in detail in the paper. Adsorption onto raw and oxidized MWCNTs was also studied. The proposed procedure allows obtaining the detection limits of 0.6, 0.6, 1.0, 0.7, 0.6, 0.5, 0.9 and 1.9 ng mL -1 for Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II), respectively. The recoveries of determined elements were about 100%. Because the analytes are not eluted from the sorbent before WDXRF analysis, the risk of contamination and loss of analytes is reduced to minimum. Moreover, because the samples are analyzed as a thin layer, the matrix effects can be neglected. The proposed preconcentration method using MWCNTs coupled with WDXRF spectrometry was successfully applied to determine trace elements in natural water samples. © 2012 Elsevier B.V.


Sroka M.,Silesian University of Technology | Zielinski A.,Polish Institute for Ferrous Metallurgy
Archives of Materials Science and Engineering | Year: 2012

Purpose: use of matrix replica method and artificial neural networks in condition assessment of materials working under creep conditions. Demonstration of scanning electron microscopy usefulness for correct assessment of the occurrence of internal damages. Design/methodology/approach: For material after long-term service the microstructural investigations were carried out on metallographic specimens and matrix replicas using light and scanning electron microscope. A computer program was used for material condition assessment. Findings: The way of material condition assessment by matrix replica method using a computer program as an example of the application of computer materials science methods was presented. The correct development of methodology for assessment of the degree of internal damages in steel working under creep conditions was found a result of verification. Critical comments on condition assessment of structure observed using light microscopy were presented. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler components operating in creep conditions. Originality/value: The presented results of changes in the mechanical properties, structure and in the precipitation processes are applied to evaluation the condition of the elements in further industrial service. © Copyright by International OCSCO World Press. All rights reserved. 2012.


Grajcar A.,Silesian University of Technology | Kuziak R.,Polish Institute for Ferrous Metallurgy
Advanced Materials Research | Year: 2011

Two 5Mn-1.5Al TRIP steels with and without Nb microaddition were developed in the present study. The steels contain bainite, martensite, interlath retained austenite and martensite-austenite islands. The paper presents the results of the compression tests carried out at various temperatures using the Gleeble simulator. To analyze the kinetics of static recrystallization in these steels, a softening kinetics were determined in a double-hit compression test. It was found that the dynamic recovery is a main thermally activated process occurring during hot deformation. The Nb microalloyed steel has higher flow stresses and peak strains than the Nb-free steel. A solute drag effect of Nb results in a slower softening kinetics of Nb containing steel. The effects of Mn on the retardation of Nb(C, N) precipitation and hot deformation characteristics are also discussed. © (2011) Trans Tech Publications, Switzerland.


Grajcar A.,Silesian University of Technology | Radwanski K.,Polish Institute for Ferrous Metallurgy | Krzton H.,Polish Institute for Ferrous Metallurgy
Solid State Phenomena | Year: 2013

The work focuses on the analysis of microstructural features of retained austenite in a thermomechanically processed Si-Al TRIP-type steel microalloyed with Nb and Ti. Austenite amount was determined using XRD and EBSD. Combined methods of LM, SEM and EBSD were applied to reveal the morphology, grain size and distribution of structural constituents. It is possible to retain 14% of ã phase enriched in C to about 1.14 wt.%. Retained austenite is uniformly located as blocky grains with a diameter up to 4.5 iμ in a fine-grained ferritic matrix or between bainitic ferrite laths as thin layers. Special crystallographic relationships between bainitic ferrite and retained austenite were identified on the basis of the analysis of misorientation angles and image quality (IQ) values. © (2013) Trans Tech Publications, Switzerland.


Grajcar A.,Silesian University of Technology | Kuziak R.,Polish Institute for Ferrous Metallurgy | Zalecki W.,Polish Institute for Ferrous Metallurgy
Archives of Civil and Mechanical Engineering | Year: 2012

Third generation of advanced high-strength steels for the automotive industry contains a high volume fraction of fine-grained ferrite, carbide-free bainite, martensite and retained austenite. The level of strength and ductility is highly dependent on the fraction and mechanical stability of austenitic phase. One of the methods to obtain an increased fraction of γ phase is trough its chemical stabilization by Mn. Two 0.17C-3Mn-1.5Al-0.2-Si-0.2Mo steels with and without Nb microaddition were developed in the present study. The steels were subjected to the thermomechanical processing designed on the basis of the DCCT diagram (deformation - continuous cooling transformation). The paper presents the results of the multi-stage compression tests and multiphase microstructures obtained as a result of the controlled multi-stage cooling. It was found that the hot workability of a new generation of AHSS is very challenging due to high values of flow stresses required. However, the thermomechanical processing enables to obtain very fine-grained bainite-based microstructures with a fraction of retained austenite up to 20%. The highest fraction of fine grains and interlath austenite was obtained for the temperature range between 400 and 450 °C. The effect of Nb results in higher flow stresses and better distribution of all the micro structural constituents. © 2012 Politechnika Wrocławska.


Zielinski A.,Polish Institute for Ferrous Metallurgy | Dobrzanski J.,Polish Institute for Ferrous Metallurgy
Archives of Materials Science and Engineering | Year: 2012

Purpose: Condition assessment of material and welded joints with regard to required utility properties of low-alloy steel for operation at elevated temperature. Design/methodology/approach: The structural and mechanical testing of parent material and welded joint at room and elevated temperature after annealing at 550°C and 600°C for 30,000 h was carried out. Findings: The effect of temperature and duration of long-term annealing on mechanical properties, hardness and structure of tested material and welded joint was determined. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler components operating in creep conditions. Originality/value: The presented results of changes in the mechanical properties, structure and in the precipitation processes are applied to evaluation the condition of the elements in further industrial service. © International OCSCO World Press. All rights reserved.


Garbarz B.,Polish Institute for Ferrous Metallurgy | Burian W.,Polish Institute for Ferrous Metallurgy
Steel Research International | Year: 2014

Basing on experimentally determined continuous cooling transformation (CCT) and time-temperature-transformation (TTT) diagrams, examination of microstructure by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques and measurements of mechanical properties an optimized chemical composition of a nanostructured bainite-austenite steel intended for production of plates is proposed. The optimized composition enables to manufacture ultra-high-strength plates up to 15 mm in thickness at relatively low cost of alloying elements and with characteristics facilitating industrial production. Experimental flat bars manufactured in semi-industrial conditions of the developed steel containing 0.56% C, 2.00% Mn, 1.76% Si, 1.29% Cr, and 0.76% Mo after transformation at 225°C for 60-72 h show good combination of mechanical properties: ultimate tensile strength over 1.9 GPa, yield strength in the range of 1.3-1.4 GPa, total elongation about 15% and hardness at the level of 600 HV. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Purpose: The aim of the study was to evaluate crack sensibility of low-alloy bainitic steel 7CrWVNb9-6(P23) and 7CrMoVTiB10-10 (P24) after welding on the basis of the results of welded gas-tight tubular wall elements and to propose changes in the manufacturing technology of the evaporator collector with supercritical working parameters of that steel group. Design/methodology/approach: On the basis of out carried macroscopic, microscopic researches in SEM using EBSD technique and material hardness measurements of circumferential and fillet welded joints the places of occurrence and the character of occurring cracks have been determined. Findings: The influence of flat bars forms, welding parameters, the nature of joint penetration on crack sensibility in circumferential and fillet welded joints of membrane walls of the evaporator collector made of new generation low-alloy bainitic steels for power engineering intended for use in boilers with supercritical working parameters. Practical implications: Obtained results and out carried reason analysis of cracking of welded joints of membrane walls made of new generation low-alloy bainitic steels for power engineering allowed to propose three ways of conduct as far as changes and selection of manufacturing technologies of evaporator collector reducing or eliminating crack sensibility of welded joints. Originality/value: The applied methodology, adopted procedure and proposed changes in the manufacturing of membrane walls, installation and repair of the evaporator collector with supercritical parameters made of new generation low-alloy bainitic steels for power engineering will be used by manufacturers in modifying and developing new applied technologies of manufacturing those elements. © by International OCSCO World Press.


Purpose: The aim of the paper was to assess the impact of the chemical composition and the cooling rate on the type of microstructure, the level of mechanical properties and crack sensitivity of welded joints of membrane walls of the evaporator collector for boilers made of new generation low-alloy bainitic steels for power engineering for the application in boilers with supercritical parameters. Design/methodology/approach: Through SEM observation using the EBSD technique occurring types of microstructures, depending on the chemical composition and cooling speed of tubes and flat bars made of 7CrMoVTiB10 - 10 steels assigned for membrane walls of the evaporator collectors for boilers have been revealed. For each types of microstructure mechanical properties have been determined. The achieved results have been referred to the designated weldability factors; chemical carbon equivalent Ce and the fracture sensitivity parameter associated with the phase transitions of Pcm. Findings: The influence of the chemical composition and the cooling rate on the formed microstructure and the corresponding level of mechanical properties and the value of carbon equivalent value Ce and the fracture sensitivity parameter due to 7CrMoVTiB10-10 steel welding. Originality/value: Applied methodology and a proposed modification of the chemical composition will be used by manufacturers in modifying and developing new technology of manufacturing membrane walls of the evaporator collectors for boilers made of new generation low-alloy bainitic steels for power engineering. © by International OCSCO World Press. All rights reserved.


Krzton H.,Polish Institute for Ferrous Metallurgy
Solid State Phenomena | Year: 2010

Steelmaking dust, collected from four different steel plants, was examined by X-ray diffraction powder technique using phase analysis. Some lead compounds, namely oxides, a silicate, a sulphate and a chloride hydroxide, were identified. The quantities of the main phase components as franklinite, magnetite, hematite and zincite were determined, applying the Rietveld method. The importance of application of the microabsorption correction was shown.

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