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Gliwice, Poland

The paper presents results of the investigation aimed at the identification both qualitative and quantitative characterization of changes occurring in the structure of cold rolled DP steel during annealing in temperature range 600-700°C. The investigation was conducted mostly by means of scanning electron microscopy combined with EBSD method. In the study, mechanisms of processes leading to subgrains formation related to static recovery, as well as to the processes connected with formation and growth of new grains in the examined material, which is characteristic feature of static recrystallization, were described. The role of the Fe3C carbide dissolution was examined which is crucial at the initial stages of as cold rolled structure transformation into austenite. Significance and the limitations of the parameters determined in EBSD analysis, such as IQ, KAM, GAM, and GOS for the quantitative characterization of the changes occurring in the structure were analyzed. These parameters are very important both for the qualitative and quantitative analysis of the structural changes occurring. They allow, among others, for determination of the fraction of deformed substructure subject to restoration processes during annealing. Examples illustrating the significance of these parameters and constraints on the analysis of recovery and recrystallization processes are presented. The paper presents results of the investigation aimed at the identification and qualitative and quantitative characterization of changes occurring in the structure of cold rolled DP steel during annealing in temperature range 600-700°C. The investigation is conducted mostly by means of SEM combined with EBSD method. The mechanisms of processes leading to subgrains formation related to static recovery as well as to the processes connected with formation and growth of new grains in the examined material are described. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Pietrzyk M.,AGH University of Science and Technology | Kuziak R.,Instytut Metalurgii Zelaza
Archives of Civil and Mechanical Engineering | Year: 2011

Jominy end quench test is considered in the paper. Finite element simulations of this test were performed including phase transformations modelling. To demonstrate the capability of the model, the numerical simulations results for two bainitic steels with different chemical composition are presented. Phase transformation model for these steels was developed on the basis of the dilatometric tests. These models were implemented in the FE code and kinetics of transformations during the Jominy test was calculated. Distributions of the structural constituents in the sample after the tests were determined. Comparison of the hardenability of the two investigated steels was made on the basis of the results of simulations. Source


Radwanski K.,Instytut Metalurgii Zelaza
Archives of Civil and Mechanical Engineering | Year: 2016

The paper presents new approach to characterizing low-carbon multiphase steels structure by means of concurrent application of optical and scanning electron microscopy with the emphasis on the latter one. Limitations of optical microscopy in material structure analysis, and the possibilities of information interchange between both methods have been discussed. The microstructure characterization is mostly based on the results obtained by means of scanning electron microscopy with wide application of EBSD method. As part of the work, fundamental constituents of multiphase steels structure with particular focus on consideration of the possibility of influencing their morphological features during thermal treatment have been systematized and described. Referring to the sheets of TRIP 700 and DP 600 steel, a capability of combining the FEG SEM analysis with EBSD method to characterize their structure was presented. EBSD method enables not only distinction of phases of various crystalline structure. Owing to analysis of parameters such as IQ, FIT, CI, KAM and misorientation angle, it is possible to differentiate constituents having different crystal structure. The method of IQ distribution curve deconvolution allows estimation of the fraction of structure constituents representing the same crystal structure. Existence of characteristic ranges of misorientation angles for selected structure constituents was proven. © 2015 Politechnika Wrocławska. Source


Burdek M.A.,Instytut Metalurgii Zelaza
Proceedings of the 10th International Conference on Technology of Plasticity, ICTP 2011 | Year: 2011

The results of 3D roughness measurements of work roll surface applied for skin passing are presented in this paper. Transfer of chosen roughness parameters from rolls on skin passed steel sheets was evaluated. Analysis of microstructure and texture of subsurface layer of steel sheets in relation to rolls topography was carried out. It was found that different work roll surface topographies with similar roughness parameter Ra insignificantly influenced on microstructure and texture of subsurface layer of steel sheets. © 2011 IBF (RWTH Aachen) & IUL (TU Dortmund). Source


Szeliga D.,AGH University of Science and Technology | Pietrzyk M.,AGH University of Science and Technology | Kuziak R.,Instytut Metalurgii Zelaza | Pidvysotskyy V.,Instytut Metalurgii Zelaza
Archives of Civil and Mechanical Engineering | Year: 2011

Development of the rheological model of copper based alloys, accounting for the state of the solid solution prior to deformation, is the objective of the paper. Two alloys are considered, Cu-1%Cr and Cu-0.7%Cr-1%Si-2%Ni. Plastometric tests were performed at various temperatures and various strain rates. Different preheating conditions before the tests were applied aimed at investigation of the effect of the initial microstructure on the flow stress. Three different rheological models for the investigated alloys were developed using inverse analysis of the tests results. Accuracy of the inverse analysis for various models was compared and the best model was selected. This model allowed comparison of the flow stress for various preheating schedules at different temperatures and strain rates, including also those which were not applied in the plastometric tests. Developed models were implemented into the finite element code FORGE based on the Norton-Hoff visco-plastic flow rule and simulations of forging of the alloys were performed. Source

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