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Burdek M.,Polish Institute for Ferrous Metallurgy
Industrial Lubrication and Tribology | Year: 2015

Purpose - This paper aims to analyze changes in the surface topography of the work rolls during skin passing. Cold rolled steel sheets are additionally subject to skin pass rolling to form an appropriate surface topography. This operation should facilitate the process of further metal forming of steel sheets, such as deep drawing, painting, etc. The surface topography of steel sheets is determined by the surface topography of the work rolls as well as the skin pass rolling parameters (rolling speed, elongation, roll force, etc.). Suitable preparation and selection of roll surface topography influences the degree of rolls wear and the surface topography of steel sheets as well. Design/methodology/approach - Two-dimensional (2D) and three-dimensional (3D) roughness measurements of work roll surface before, during and after finishing of skin pass rolling of steel sheets are presented in the paper. The measurements were performed on four sets of work rolls with different surface topography. Findings - The appearance of the surface of rolls obtained from the analysis of 3D roughness, the values of selected parameters of the 3D roughness and relative changes of the roughness parameter Ra/Sa depending on the length of the skin passed steel sheets are presented. Practical implications - The wear of rolls is different depending on work surface topography. Originality/value - The aim of this paper is to analyze changes in the surface topography of the work rolls during skin passing. It was expected that the surface of work rolls with more summits at similar average roughness Ra will change much faster than the surface with fewer summits. For this purpose, preliminary tests were performed in an industrial environment on four pairs of work rolls, including two pairs of rolls that were hard chromium-plated. © Emerald Group Publishing Limited.

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.

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.

Chen H.,Technical University of Delft | Kuziak R.,Polish Institute for Ferrous Metallurgy | Van Der Zwaag S.,Technical University of Delft
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

Cyclic phase transformation experiments are performed in a series of Fe-C-xMn, Fe-C-Mn-xNi, and Fe-C-MnxCo alloys to study the effect of alloying elements on the length of the stagnant stage during a cyclic partial phase transformation in the austenite-ferrite two-phase region. The length of stagnant stage increases linearly with the increasing Mn or Ni concentration, while Co has no effect. It was experimentally proven that the effects of alloying elements on the length of stagnant stage are additive, and the experimental results matched the predictions of the local equilibrium model very well. © The Minerals, Metals & Materials Society and ASM International 2013.

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