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1

Influence of Material State on Austenitic Transformation in HSLA-Type Steel

100%

Wojtacha A. , Morawiec M. , Opiela M.

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tom Vol. 18, no 4

66--75

EN

The paper presents the results of research on the influence of the material condition – HSLA steel with Ti and Nb microadditions – on the course of the austenitic transformation. In order to determine the kinetics of phase transformations occur in steel during individual stages of the austenitic transformation, tests were carried out using a Bähr 805 A/D dilatometer. In order to determine the influence of hot plastic deformation on the course of the austenitic transformation, plastometric tests were carried out using the Gleeble 3800 thermomechanical simulator. For detailed microstructural analysis, microscopic examinations were carried out using the light microscope and the scanning electron microscope. The obtained results were compared with hardness measurements. The tests carried out showed significant differences in the course of the austenitic transformation and the values of critical temperatures for steel before and after using the plastic deformation. The Ac1 temperature for steel in the as-cast state is 850°C and the Ac3 temperature is 950°C. As the annealing temperature increases, the hardness increases from 210 HV100 for a temperature of 700°C to 260 HV100 for a temperature of 920°C. Knowledge about the phase transformations of supercooled austenite is extremely important, especially for newly developed steels, hence the aim of the work is to analyze the atypical course of the austenitic transformation of HSLA steels and to determine the influence of deformation on the austenitic transformation during heating.

2

The Numerical Simulation of Aviation Structure Joined by FSW

88%

Lacki P. , Adamus K. , Winowiecka J.

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tom Vol. 64, iss. 1

387--392

EN

This work presents a numerical simulation of aviation structure joined by friction stir welding, FSW, process. The numerical simulation of aviation structure joined by FSW was created. The simulation uses thermomechanical coupled formulation. The model required creation of finite elements representing sheets, stiffeners and welds, definition of material models and boundary conditions. The thermal model took into account heat conduction and convection assigned to appropriate elements of the structure. Time functions were applied to the description of a heat source movement. The numerical model included the stage of welding and the stage of releasing clamps. The output of the simulation are residual stresses and deformations occurring in the panel. Parameters of the global model (the panel model) were selected based on the local model (the single joint model), the experimental verification of the local model using the single joint and the geometry of the panel joints.

3

Influence of thermo-plastic deformation on grain size of high-manganese austenitic X11MnSiAl17-3-1 steel

75%

Dobrzański L. A. , Czaja M. , Borek W. , Labisz K.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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tom Vol. 61, nr 2

169--174

EN

Purpose: The aim of the paper is to compare fragmentation of grains after thermo-mechanical treatment using Gleeble 3800 simulator of high-manganese austenitic X11MnSiAl7-1-3 steel. Design/methodology/approach: The hot-working behaviour was determined 4- and 8-stage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermo-mechanical simulator. The comparison between two type of thermo-mechanical treatment has been established based on microstructure research and X-ray diffraction analysis. Findings: It was found that steel X11MnSiAl7-1-3 in initial state and after thermo-mechanical treatment on Gleeble simulator has homogeneous austenite structure. Compression tests were realized in the temperature range from 850 to 1050°C with the true strain 4x0.23 for 4-stage process, and 0.4 in the first deformation, and 0.25 and 0.2 in the following deformations for 8-stage process. The multi-stage compression examination gives the possibility to refine the austenite microstructure. Based on microstructures research were found that this process perfectly led to fragmentation of the material structure which may result in the ideal material properties. Practical implications: The obtained microstructure after Gleeble simulations can be useful in determination of power-force parameters of hot-rolling for thin sheets to obtain fine-grained austenitic microstructures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels were investigated.

4

Structure of X11MnSiAl17-1-3 steel after hot-rolling and Gleeble simulations

63%

Dobrzański L. , Borek W. , Czaja M. , Mazurkiewicz J.

Archives of Materials Science and Engineering

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2013

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tom Vol. 61, nr 1

13--21

EN

Purpose: The aim of the paper is to compare results after thermo-mechanical simulation using Gleeble 3800 and hot-rolling on LPS module of high-manganese austenitic X11MnSiAl7-1-3 steel. Design/methodology/approach: The hot-working behaviour was determined in continuous, 4- and 8-stage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermo-mechanical simulator and LPS module for semi-industrial hot rolling. The comparison between two processes has been established based on microstructure research and X-ray diffraction analysis. Findings: It was found that austenite microstructure with numerous annealing twins in the initial state was obtained. 4-stage compression tests were realized in the temperature range from 850 to 1050°C with the true strain 4x0.23. 8-stage compression test were performed in the same temperature range and with true strain of 0.4 in the first deformation, and 0.25 and 0.2 in the following deformations. The multi-stage compression examination gives the possibility to refine the austenite microstructure. Based on this research hot-rolling on LPS module in the temperature range from 1100°C to 850°C was realized. Based on microstructures research were found that this process is not perfect due to longer intervals between successive passes and inability to control the temperatures of following passes. Practical implications: The obtained stress-strain curves relationship and microstructure after Gleeble simulations can be useful in determination of power-force parameters of hot-rolling for thin sheets to obtain fine-grained austenitic microstructures. Originality/value: The hot-working behavior and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels were investigated.