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PL
W pracy przedstawiono analizę wpływu temperatury (1000 i 1200°C) i szybkości izotermicznego ściskania na gorąco (ε =0,1, 1,0 i 10,0 s-1) na przebudowę mikrostruktury drobnoziarnistego stopu na osnowie fazy międzymetalicznej Ni3Al z dodatkami stopowymi cyrkonu i boru. W wyniku przeprowadzonej obróbki obserwowano efekty rekrystalizacji dynamicznej/postdynamicznej, której udział rósł wraz ze zmniejszeniem szybkości odkształcania i wzrostem temperatury procesu.
EN
The analysis of temperature (1000 and 1200°C) and rate of isothermal hot compression (ε =0.1, 1 i 10 s-1)on the microstructure changes of Ni3Albased intermetallic alloy with zyrconium and boron addition wasshownin the paper. It was observed that the performed treatment has influence on dynamic/postdynamic recrystallization which participation increase with decreasing rate of strain and increasing of process temperature.
PL
W pracy przedstawiono analizę wpływu temperatury i prędkości walcowania na gorąco na ewolucję mikrostruktury wcześniej uplastycznionego, drobnoziarnistego stopu na osnowie fazy międzymetalicznej Ni3Al z dodatkami stopowymi cyrkonu i boru. W efekcie przeprowadzonej obróbki plastycznej na gorąco stwierdzono istotny przyrost umocnienia, względem materiału wyjściowego. Analiza EBSD wykazała lokalną przebudowę struktury materiału na drodze rekrystalizacji dynamicznej w temperaturze 1280OC i przy prędkości odkształcania 17 m/min.
EN
Temperature and deformation strain rate structure changes in hot-rolled, fine-grained Ni3Al-based intermetallic alloy with zyrconium and boron addition were analyzed in the paper. The conducted hot-working leads to significant increase of hardening level than for material in “initial” stage. The EBSD analysis shows structure change by dynamic recrystallization at temperature 1280OC and strain rate 17 m/min.
3
Content available remote Structure of X11MnSiAl17-1-3 steel after hot-rolling and Gleeble simulations
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.
EN
Purpose: The purpose of the article is to present the results of research of the effect of thermal and thermoplastic working on the structure of high-manganese austenitic TWIP steels. Design/methodology/approach: Plastometric tests were performed with DSI (Dynamic System Inc.) Gleeble 3800 instrumentation being the equipment of the Scientific and Didactic Laboratory of Nanotechnology and Materials Technologies of the Institute of Engineering Materials and Biomaterials. Changes in the microstructure after individual stages of hot plastic deformation were determined on the basis of detailed microstructure tests with the light microscope and scanning electron microscope. An X-ray phase qualitative analysis of the examined materials in the condition after casting and after thermoplastic working was carried out with the XPert diffractometer by Philips. Findings: It was concluded based on the tests performed that the structure of the examined austenitic high-manganese steel in the initial condition is represented by austenite with numerous annealing twins. The results obtained for investigations in a continuous compression test will enable to establish power and energy parameters and design a hot compression process, consisting of several phases, of axisymmetric specimens, simulating the final rolling passes. Practical implications: By elaborating the detailed data concerning structural changes and power and energy parameters of the thermoplastic working process of the investigated high-manganese austenitic TWIP steel type, it will be possible to design appropriately the final passes of the hot rolling process to obtain an optimum size of grains, which will in turn influence the improved strength properties of the investigated high-manganese austenitic X11MnSiAl25-1-3 steel. Originality/value: The application of thermoplastic working of high-manganese austenitic TWIP steel.
EN
Purpose: In this paper the result of laser surface feeding or remelting is discussed. The remelted layers which were formed on the surface of the investigated hot work steel were examined and analyzed metallographically and analyzed using a hardness testing machine. The resistance research has been done on the CSM Instruments. Design/methodology/approach: In this paper the results of laser treatment techniques applied in metal surface technology are presented and discussed. There is presented laser treatment with feeding or remelting of hot work tool steel X40CrMoV5-1 with ceramic powders especially - Al2O3 and Si3N4, as well as results of laser remelting influence on structure and properties of the surface of the hot work steel, carried out using the high power diode laser (HPDL). Findings: On the basis of the wear abrasion tests carried out on hot work tool steel it could be found that each of those specimens is characterized by different resistance for the same powders and the power of the laser beam. The metallographic investigations on light microscope show that during feeding or remelting the hot work tool steel with the ceramic powder layer in the whole range of the laser power values used 1.2-2.3 kW the obtained bead face is characteristic of the high roughness, multiple pores, irregularity. Practical implications: The resistance to abrasive wear is a practical aim of this work as well as improvement of hardness as a very important properties for practical use. It is necessary to continue the research to determine feeding or remelting parameters for demanded properties of hot work tool steels surface layers. Originality/value: Laser feeding or remelting by using HPDL laser (High Power Diode Laser) and selected ceramic powders can be very attractive for industries.
EN
Purpose: The aim of the paper is to determine the influence of hot-working conditions on microstructure evolution and phase composition of new-developed high-manganese austenitic TRIP-type steels. Design/methodology/approach: The hot-working behaviour was determined in continuous and multistage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermo-mechanical simulator. The processes controlling work hardening and removing it were identified by microstructure evolution observations in different stages of compression with the amount of true strain 4x0.23. Phase composition of steels was confirmed by X-ray diffraction analysis. Findings: It was found that they have austenite microstructure with numerous annealing twins in the initial state. Continuous compression tests realized in the temperature range from 850 to 1050°C with the strain rate of 0.1, 1 and 10 s-1 enabled determination of yield stress values and values of εmax deformations - corresponding to maximum flow stress. The investigated steels are characterized by high values of flow stress from 120 to 380 MPa. Results of the multi-stage compression proved that applying the true strain 4x0.23 gives the possibility to refine the austenite microstructure. Research limitations/implications: To determine in detail the microstructure evolution during industrial rolling, the hot-working schedule should take into account real number of passes and higher strain rates. Practical implications: The obtained microstructure - hot-working conditions relationships and stress-strain curves can be useful in determination of power-force parameters of hot-rolling for sheets with fine-grained austenitic structures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic TRIP-type steels with Nb and Ti microadditions were investigated.
7
Content available remote Hot deformation behavior and softening kinetics of Ti–V–B microalloyed steels
EN
Results of the effect of deformation parameters on the hot-deformation behavior and softening kinetics of two Ti–V–B-microalloyed steels were presented in the paper. The investigated steels are assigned to production of forged elements for the automotive industry by thermo-mechanical treatment. Research was conducted by compression test at elevated temperature. Hot compression test was performed using the Gleeble 3800 thermomechanical simulator at the temperature range from 900 °C to 1100 °C and strain rate of 1, 10 and 50 s−1. The σ–ε curves were determined on the basis of continuous compression and double-hit compression tests.
8
Content available remote The influence of hot-working conditions on a structure of high-manganese steel
EN
The high-manganese steels with the austenitic structure belong to a group of modern steels predicted to use in the automotive industry. The chemical composition of the steel containing 25% Mn, solution hardened by Si and Al was developed. Microadditions of Nb and Ti introduced into the steel creating stable nitrides and carbides should act by precipitation hardening and inhibit a grain growth of recrystallized austenite. The aim of the work was to determine the influence of various hot-working conditions on a structure of the investigated steel. The processes controlling work-hardening and removing strengthening after finishing the hot-working were identified. The preliminary upset forging by the use of eccentric press with a degree of deformation in a range of 20 to 60% and at temperatures of 850 and 1000 C was carried out. On the basis of determined conditions the multi-stage axial compression tests ensuring the finegrained austenite structure were performed.
PL
Stale wysokomanganowe o strukturze austenitycznej należą do grupy nowoczesnych stali przewidzianych do zastosowania w przemyśle motoryzacyjnym. Opracowano skład chemiczny stali zawierającej 25% Mn, umacnianej roztworowo przez Si i Al. Mikrododatki Nb i Ti wprowadzone do stali, tworząc stabilne azotki i węgliki powinny powodować umocnienie wydzieleniowe i hamować rozrost ziaren austenitu zrekrystalizowanego. Celem pracy było określenie wpływu zmiennych warunków obróbki plastycznej na gorąco na strukturę badanej stali. Zidentyfikowano procesy kontrolujące umocnienie odkształceniowe i usuwające umocnienie po zakończeniu obróbki plastycznej na gorąco. Przeprowadzono wstępne spęczanie w temperaturach 850 i 1000 C przy użyciu prasy mimośrodowej, stosując stopień gniotu w zakresie od 20 do 60%. Na podstawie wyznaczonych warunków przeprowadzono kilkustopniowe próby ściskania osiowosymetrycznego zapewniające uzyskanie drobnoziarnistej struktury austenitu.
9
Content available remote Microstructure evolution and phase composition of high-manganese austenitic steels
EN
Purpose: The aim of the paper is to determine the influence of hot-working conditions on microstructure evolution and phase composition of new-developed high-manganese austenitic steels. Design/methodology/approach: Determination of processes controlling strain hardening was carried out in continuous compression test using Gleeble 3800 thermo-mechanical simulator. Evaluation of processes controlling work hardening and occurring after deformation at 900°C were identified by microstructure observations of the specimens solution heat-treated after plastic deformation to a true strain equal 0.23, 0.50 and 0.91. Phase composition of steels was confirmed by X-ray diffraction analysis. Findings: The steels have a fine-grained austenite microstructure with many annealing twins to a temperature of about 1000°C. The initiation of dynamic recrystallization occurs already after true deformation equal 0.29. Participation of fine grains arranged in a matrix of dynamically recovered grains essentially increases after increasing true strain to 0.5. Fully dynamically recrystallized microstructure of steel can be obtained after the true strain equal 0.9. The conditions of hot-working influence phase state of investigated steels. Steel no. 1 keeps stable austenite microstructure independently from conditions of plastic deformation. Steel with initial bi-phase microstructure keeps a certain portion of ε martensite, yet dependant on conditions of hot-working. Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of microstructure evolution in subsequent stages of multi-stage compression test should be investigated. Practical implications: The obtained microstructure- hot-working conditions relationships and stress-strain curves can be useful in determination of power-force parameters of hot-rolling for sheets with fine-grained austenitic structures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels with Nb and Ti microadditions were investigated.
10
EN
Purpose: The aim of the paper is to determine the influence of hot deformation conditions on σ - ε curves and structure changes of new-developed high-manganese austenitic steels. Design/methodology/approach: The force-energetic parameters of hot-working were determined in hot-compression tests performed in a temperature range of 850 to 1050° C by the use of the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work hardening at 850° C were identified by microstructure observations of the specimens water-quenched after plastic deformation to a true strain equal 0.22, 0.51 and 0.92. Findings: At initial state the steel containing 3% of Si and Al possesses homogeneous austenite structure with many annealing twins. Increased up to 4% Si concentration and decreased to 2% Al concentration result in a presence of some fraction of ε martensite plates. For applied deformation conditions, the values of flow stress vary from 250 to 450MPa - increasing with decreasing deformation temperature. A relatively small values of ε max deformation at temperatures of 1050 and 950° C allow to suppose that in this range of temperature, to form a fine-grained microstructure of steels, dynamic recrystallization can be used. At a temperature of 850° C, the dynamic recrystallization leads to structure refinement after true strain of about 0.51. Research limitations/implications: To determine in detail the hot-working behaviour of developed steels, a progress of recrystallization as a function of time at deformation temperature should be investigated. Practical implications: The obtained stress-strain curves can be useful in determination of power-force parameters of hot-rolling of high-manganese austenitic steels. Originality/value: The hot-working behaviour of new-devoloped high-manganese austenitic steels containing Nb and Ti microadditions was investigated.
11
Content available remote Hot-working behaviour of high-manganese austenitic steels
EN
Purpose: The work consisted in investigation of newly elaborated high-manganese austenitic steels with Nb and Ti microadditions in variable conditions of hot-working. Design/methodology/approach: Determination of processes controlling strain hardening was carried out in continuous compression test using Gleeble 3800 thermo-mechanical simulator. Findings: It was found that they have austenite microstructure with numerous annealing twins in the initial state. Continuous compression tests realized in the temperature range from 850 to 1050*C with the strain rate of 10s -1 enabled determination of yield stress values and values of εmax deformations-corresponding to maximum flow stress. It was found that initiation of dynamic recrystallization requires true strain equal at least 0.29. Holding of steel after plastic deformation allowed determining the progress of recrystallization in the function of isothermal holding time. Determined half-times of recrystallization at 900oC after deformation with 25% of reduction are equal 32 and 17s for 27Mn-4Si-2Al-Nb-Ti and 26Mn-3Si-3Al-Nb-Ti steel, respectively. Several-stage compression tests with true strain of 0.29 permit to use dynamic recrystallization for shaping fine-grained microstructure of steel in the whole range of deformation temperature. Decreasing true strain to 0.23 limits the course of dynamic recrystallization to two first deformation cycles. In two final cycles of deformation, as well as in the whole range of hot-working realized with true strain of 0.19-dynamic recovery is the process controlling strain hardening. Practical implications: The obtained microstructure-hot-working conditions relationships and stress-strain curves can be useful in determination of power-force parameters of hot-rolling for sheets with fine-grained austenitic structures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels with Nb and Ti microadditions were investigated.
PL
W pracy zbadano zachowanie się nowo opracowanej stali C-Mn-Si-Al z mikrododatkami Nb i Ti w warunkach obróbki plastycznej na gorąco. Wyznaczono krzywe a-e oraz ujawniono strukturę austenitu pierwotnego próbek odkształconych do zadanego odkształcenia plastycznego oraz wytrzymanych izotermicznie po odkształceniu przez 10 s. Na tej podstawie wyznaczono warunki kilkuetapowego ściskania symulującego końcowe przepusty walcowania.
EN
Behaviour of new-developed C-Mn-Si-Al steel with Nb and Ti microadditions in hot-working conditions was investigated in the work The o-e curves were determined and primary austenite structures of the specimens deformed to a given strain and isothermally held for 10 s after deformation were revealed. On this basis, the conditions of multistage compression simulating final rolling passes were determined.
13
Content available remote Thermo-mechanical processing of high-manganese austenitic TWIP-type steels
EN
The high-manganese austenitic steels are an answer for new demands of automotive industry conceming the safety of passengers by the use of materials absorbing high values of energy during collisions. The chemical compositions of two high-manganese austenitic steels containing various Al and Si concentrations were developed. Additionally, the steels were microalloyed by Nb and Ti in order to control the grain growth under hot-working conditions. The influence of hot-working conditions on recrystallization behaviour was investigated. On the basis of initial investigations realized by hot upsetting the thermo-mechanical conditions resulting in a fine-grained structure were designed. The [...] curves and identification of thermally activated processes controlling work-hardening by the use of the Gleeble simulator were determined. It was found that the thermo-mechanical treatment conditions influence a phase composition of the investigated steels after solution heat treatmenl.
PL
Wysokomanganowe stale austenityczne stanowią odpowiedź dla nowych żądań przemysłu motoryzacyjnego dotyczących bezpieczeństwa pasażerów przez zastosowanie materiałów absorbujących dużą ilość energii w warunkach kolizji. Opracowano składy chemiczne dwóch wysokomanganowych stali austenitycznych zawierających różne stężenie Al i Si. Dodatkowo, w celu kontroli rozrostu ziaren w warunkach obróbki plastycznej na gorąco stale zawierają mikrododatki Nb i Ti. Zbadano wpływ warunków obróbki plastycznej na gorąco na przebieg rekrystalizacji. Na podstawie badań wstępnych zrealizowanych przez spęczanie na gorąco zaprojektowano warunki obróbki cieplno-mechanicznej prowadzące do uzyskania drobnoziarnistej struktury. Przy zastosowaniu symulatora Gleeble wyznaczono krzywe [...] oraz aktywowane cieplnie procesy kontrolujące umocnienie odkształceniowe. Stwierdzono, że warunki obróbki cieplno-mechanicznej mają wpływ na skład fazowy badanych stali po przesycaniu.
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