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PL
W artykule przedstawiono wyniki badań, w których określono warunki tarcia podczas kształtowania stali C45 w temperaturze 1150°C. Badania przeprowadzono z wykorzystaniem smarów na bazie szkła: szkło wodne, mieszanina szkła wodnego i grafitu oraz proszek szklany. Celem badań było wyznaczenie czynnika tarcia m. Wartości czynników tarcia wyznaczono na podstawie porównania wymiarów próbek spęczanych doświadczalnie z wynikami symulacji numerycznych. Szukaną wartość czynnika tarcia określano na podstawie minimalizacji funkcji celu.
EN
The paper presents the results of investigations in which friction conditions were determined during forming of C45 steel at 1150 °C. The research was conducted using glass-based lubricants: water glass, a mixture of water glass and graphite, and glass powder. The aim of this research was determining values of friction factors m. The values of friction factors were determined on the basis of the comparison of the dimensions of the experimental samples with the results of numerical simulations. The target value of friction factor was determined on the basis of minimizing the objective function.
2
Content available Rozwój technologii regulowanego walcowania stali
EN
The experience of many generations of researchers; metallurgists and designers have resulted in new types of steel, they called it: third generation.
PL
W artykule przybliżono postępy dokonane w pracach nad rozwojem technologii regulowanej przeróbki plastycznej na gorąco, które doprowadziły do wytwarzania stali o wielofazowej strukturze z wymaganym udziałem, rozmieszczeniem i morfologią poszczególnych składników strukturalnych. Wymaga to odpowiedniego sterowania procesami zachodzącymi już podczas obróbki plastycznej na gorąco, w zakresie stabilności austenitu i kontrolowanego przebiegu chłodzenia w warunkach przemiany fazowej austenitu przechłodzonego. Wytwarzane obecnie w tej technologii stale, tzw. trzeciej generacji, wymienione w końcowej części publikacji, są stosowane na elementy konstrukcyjne wymagające połączenia wysokiej wytrzymałości i plastyczności, zdolne do pochłaniania energii w warunkach odkształcenia plastycznego z dużymi prędkościami. Obecnie regulowane walcowanie, obok hartowania izotermicznego na bainit dolny, jest też jednym z finalnych zabiegów obróbki stali konstrukcyjnych wysokowęglowych oraz narzędziowych zarówno do pracy na zimno jak i szybkotnących.
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.
EN
Deformation softening is quite often observed during hot working of different alloys. Steels, aluminium, titanium or nickel alloys can demonstrate a decrease in flow stress under active deformation at constant temperatures and strain rates. Though the background microstructural mechanisms as well as the softening rates can be quite different, the treatment of such processes requires special attention. Deformation softening can cause significant non-uniformity of the metal flow resulting in flow localization, formation of shear bands and variation of the microstructure across the workpiece. This paper is devoted to the investigation of the specific issues which arise in this respect in FEM simulation of processes involving softening. The possible role of softening in shear band formation is studied using numerical simulation and physical modelling. The effect of the softening rate on the probability of flow localization is discussed. The interplay of deformation softening with the stain rate and temperature sensitivity is demonstrated using as an example the simulation of Equal Channel Angular Pressing (ECAP). An approach to account for the deformation softening in FEM simulations via process modelling of the microstructure refinement is proposed.
PL
Zmiękczanie podczas odkształcenia jest często obserwowane podczas obróbki plastycznej na gorąco różnych stopów. Stale, stopy aluminium, tytanu lub niklu mogą wykazać zmniejszenie naprężenia płynięcia w warunkach czynnego odkształcania przy stałej temperaturze i prędkości odkształcenia. Jednak mechanizmy w tle jak również prędkości zmiękczenia mogą być bardzo różne, stąd analiza takich procesów wymaga szczególnej uwagi. Zmiękczenie podczas odkształcenia może powodować znaczną niejednorodność płynięcia metalu prowadzącą do lokalizacji płynięcia, tworzenia pasm ścinania i zróżnicowania mikrostruktury w całym odkształcanym elemencie. Niniejsza praca poświęcona jest badaniu konkretnych problemów, pojawiających się w tym zakresie podczas symulacji metodą elementów skończonych procesów z udziałem zmiękczania. Możliwa rola zmiękczenia w powstawaniu pasm ścinania badana jest za pomocą symulacji numerycznych i modelowania fizycznego. Omawiany jest wpływ prędkości zmiękczania na prawdopodobieństwo lokalizacji płynięcia. Wzajemne oddziaływanie zmiękczania podczas odkształcenia z szybkością odkształcenia i temperaturą, wykazano stosując jako przykład symulację wyciskania przez kanał kątowy. Zaproponowano podejście do ujęcia zmiękczania podczas odkształcenia w symulacji metodą elementów skończonych poprzez modelowanie procesów rozdrobnienia mikrostruktury.
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.
6
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.
9
Content available remote Hot-working of advanced 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: The force-energetic parameters of hot-working were determined in continuous and multi-stage compression test performed in temperature range of 850 to 1100°C using the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work-hardening were identified by microstructure observations of the specimens compresses to the various amount of deformation (4x0.29, 4x0.23 and 4x0.19). The microstructure evolution in successive stages of deformation was determined in metallographic investigations using light, scanning and electron microscopy as well as X-ray diffraction. Findings: The investigated steels are characterized by high values of flow stresses from 230 to 450 MPa. The flow stresses are much higher in comparison with austenitic Cr-Ni and Cr-Mn steels and slightly higher compared to Fe-(15-25)Mn alloys. Increase of flow stress along with decrease of compression temperature is accompanied by translation of εmax strain in the direction of higher deformation. Results of the multi-stage compression proved that applying the true strain 4x0.29 gives the possibility to refine the austenite microstructure as a result of dynamic recrystallization. In case of applying the lower deformations 4x0.23 and 4x0.19, the process controlling work hardening is dynamic recovery and a deciding influence on a gradual microstructure refinement has statical recrystallization. The steel 27Mn-4Si-2Al-Nb-Ti has austenite microstructure with annealing twins and some fraction of ε martensite plates in the initial state. After the grain refinement due to recrystallization, the steel is characterized by uniform structure of γ phase without ε martensite plates. 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 relationships can be useful in the determination of power-force parameters of hot-rolling and to design a rolling schedule for high-manganese steel sheets with fine-grained austenitic structures. Originality/value: The hot-deformation resistance and microstructure evolution in various conditions of hot-working for the new-developed high-manganese austenitic steels were investigated.
PL
Celem pracy jest analiza doświadczalna uplastycznienia spieku czystego aluminium w podwyższonych temperaturach. Badanie polegało na badaniu naprężeń podczas odkształcenia plastycznego spieków o różnej porowatości początkowej. Przedstawiono zależność naprężenia uplastyczniającego materiału spiekanego od naprężenia uplastyczniającego dla materiału bazowego.
EN
The purpose of the paper is to analyze the yielding of pure aluminum P/M specimen at high temperatures. The identification is based on strain and stress measurements during plastic deformation of P/M specimen for various initial porosities. The relation between apparent yield stress of P/M material and the base material is presented.
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 Microstructural heterogeneity of forged rolled rings
EN
Purpose: The paper presents the processes which condition the quality of steel cast strands and properties of rolled products. It touches upon the technology of small-size rings manufacture from the 42CrMo4 steel used for the production of rolling bearings and toothed rings. Design/methodology/approach: Investigations were made on the 42CrMo4 steel based process of small-size rings manufacture of weight not exceeding 100 kg and the internal diameter up to 600 mm. Findings: Microstructure heterogeneity has been proven on the cross section of rods and rings under hot rolling and thermal treatment. Non-uniformity in hardness distribution was found on the hot rolled rings' face surface and cross section. Final products made from rings with heterogeneous properties characterize: difficulties with machining, cracking during surface hardening and decrease of life time. After the process modification, the rings' microstructure homogeneity and advantageous hardness distribution were obtained. Practical implications: A good quality of final rings after heat treatment is obtained in the case of charge characterized by a uniform pearlitic/ferritic microstructure. After the process technology modification, the rings' microstructure homogeneity and advantageous hardness distribution were obtained. Originality/value: The minimum processing degree in the rolling of rod products should guarantee obtaining a homogeneous microstructure on the rings cross section and properties which would ensure a good quality and the required functional properties of the final products.
PL
W artykule przedstawiono wyniki badań plastometrycznych ołowiu w gatunku Pb1. Na wykresach zestawiono krzywe płynięcia tego metalu w temperaturach 20, 40 i 60°C, uzyskane przy prędkościach odkształcenia od 0,1, 1 i 10 s[do potęgi -1] w zakresie intensywności odkształcenia od O do 1. Korzystając z metod optymalizacji wyznaczono również szereg równań konstytutywnych (2) - (9) opisujących otrzymane krzywe płynięcia. Równania te zostaną wykorzystane w obliczeniach numerycznych, bazujących na MES, nowego procesu kształtowania metodą walcowania klinowo-rolkowego.
EN
Results of compression tests of Pb1 lead grade are presented in this paper. Experimental works were curried out at: temperature of 20, 40 and 60°C, strain rate of 0.1, 1 and 10 s [ -1st power of s], effective strain of 0- 1. Flow curves of analyzed metal are given on figures. Also equations (2) - (9) determining obtained flow curves were calculated using optimization method. These equations will be used for FEM simulation of new forming process by wedge-rolls rolling.
PL
Badano wpływ mikrostruktury na wytrzymałość zmęczeniową dwufazowych stopów tytanu alfa+beta (Ti-6Al-4V, Ti-6Al-2Mo-2Cr i Ti-6Al-5Mo-5V-1Cr-1Fe), zmieniając parametry geometryczne płytkowej fazy alfa poprzez dobór odpowiednich parametrów obróbki cieplnej. Badano również wływ temperatury i stopnia odkształcenia oraz temperatury wyżarzania na wytrzymałość zmęczeniową odkuwek ze stopów Ti-6Al-4V i Ti-6Al-2Mo-2Cr. Określono optymalne wartości parametrów geometrycznych mikrostruktury i parametrów przeróbki plastycznej na gorąco dwufazowych stopów tytanu dla uzyskania maksymalnej wytrzymałości zmęczeniowej.
EN
In the course of the study the influence of a microstructure on fatigue strength of two-phase alpha+beta titanium alloys (Ti-6Al-4V, Ti-6Al-2Mo-2Cr and Ti-6Al-5Mo-5V-1Cr-1Fe) was investigated. Geometrical parameters of the lamellar microstructure of alpha-phase were varied by means of application of various heat treatment conditions and their effect on fatigue strength was examined. The influence of deformation degree and temperature and annealing temperature on fatigue strength of forgings made of two-phase martensitic titanium alloys Ti-Al-4V and Ti-6Al-2Mo-2Cr was also examined. Optimum values of basic geometrical parameters of the microstructure of titanium alloys and hot working parameters for obtaining maximum fatigue strength were determined.
PL
Opór zużycia ściernego metali zależy od wielu czynników. W dużym stopniu wpływ na to ma wstępna obróbka plastyczna na gorąco i na zimno. Sposób wstępnego odkształcenia w stanie zimnym i jego wpływ na zużycie ścierne jest przedmiotem szczególnego zainteresowania, ponieważ powoduje duże zmiany strukturalne i utwardzenie obrabianego materiału.
EN
Presented are preliminary results of investigations of the structure of hot extruded aluminium powder based composites reinforced with 1.5% by mass additive of Al2O3 fibres. Highly densified composite with advantageous structure has been obtained.
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