31 research outputs found
Plastic forming of magnesium alloys
W artykule, kt贸ry ma charakter przegl膮dowy, wskazano na rosn膮ce zainteresowanie w ostatnich latach stopami magnezu do zastosowa艅 na elementy 艣rodk贸w transportu. Podano klasyfikacj臋 stop贸w magnezu do obr贸bki plastycznej, metody wytwarzania wyrob贸w drog膮 walcowania, wyciskania i kucia oraz wskazano trudno艣ci przy realizacji proces贸w kszta艂towania plastycznego. W badaniach stop贸w AZ31, AZ61, AZ80 i WE43 przedstawiono relacje pomi臋dzy struktur膮, a parametrami odkszta艂cania. Wskazano na wyst臋powanie dw贸ch mechanizm贸w odkszta艂cania w zale偶no艣ci od temperatury: po艣lizgu i bli藕niakowania. Podano zale偶no艣ci pomi臋dzy wielko艣ciami charakteryzuj膮cymi plastyczno艣膰 a parametrem Zenera鈥揌ollomona. Przedstawiono wyniki prowadzonych prac w zakresie proces贸w obr贸bki plastycznej stop贸w magnezu - walcowania, kucia oraz wyciskania oraz przyk艂ady wykonanych wyrob贸w.The article that is a review indicates a growing interest in magnesium alloys concerning applications related to the elements of means of transport over the last few years. It specifies a classification of magnesium alloys intended for plastic forming as well as rolling, extrusion and forging production methods, and, additionally, difficulties connected with plastic forming processes. In the tests of the alloys AZ31, AZ61, AZ80 and WE43 there are presented relations between a structure and deformation parameters. The study shows two deformation mechanisms, i.e. slip and twinning that appear depending on the temperature. Furthermore, the paper lists relationships between the values describing plasticity and the Zener-Hollomon parameter. It also presents results of researches performed within the scope of magnesium alloy plastic forming processes - rolling, forging and extrusion, and examples of manufactured products
DEFORMATION MODE IN AZ31 MAGNESIUM ALLOY DURING COMPRESSION TESTS
Abstract Usage of magnesium alloys constantly increase, especially in the area of automotive industry. Classification of magnesium alloys for forming, production process by rolling, extrusion and forging have been presented. Moreover, the difficulties in magnesium manufacturing have been presented as well. The relations between microstructure and deformation parameters in AZ31 magnesium alloy have been studied. Two main deformation processes: twinning and slipping have been shown. The changes in the plastic characteristics as a function of the Zener-Hollomon parameter have been presented. The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated AZ31 type alloy. The results will constitute the basis for modelling the structural changes
Electrochemical Corrosion of Magnesium Alloy AZ31 with Additive Lithium
The purpose of performed tests was evaluation of resistance to electrochemical corrosion of extruded magnesium alloy AZ31 with additive of 4.5% Li. Corrosion tests were performed in 0.01-2.0 M NaCl solutions. Potentiodynamic tests enabled to register polarisation curves. With application of stereoscopic microscope Nikon SMZ745T and electron scanning microscope Hitachi S-4200, the surface of the alloy was observed after immersion tests performed in 1-6 days. Results of performed tests prove explicitly deterioration of corrosion properties of the alloy with the increase of molar concentration of NaCl solution. It can be seen that corrosion process is intensive and that intensity increases with the increase of solution concentration and extension of exposure time
Simulation of closing and welding of stock material voids during sheet and bar rolling
W artykule przedstawiono model numeryczny oraz wybrane wyniki przeprowadzonych symulacji wst臋pnej fazy walcowania pr臋t贸w oraz blach. Zastosowano modele geometryczne wlewk贸w ci膮g艂ych, w kt贸rych wprowadzono modelowe nieci膮g艂o艣ci materia艂owe. Model i parametry symulacji odpowiada艂y warunkom walcowania na uruchomionej w Instytucie Metalurgii 呕elaza linii LPS. Przeanalizowano rozk艂ad stanu napr臋偶enia w kotlinie walcowniczej, jak r贸wnie偶 zmiany kszta艂tu modelowych nieci膮g艂o艣ci materia艂owych. Na podstawie analizy uzyskanych wynik贸w symulacji sformu艂owano zalecenia dotycz膮ce doboru warunk贸w pocz膮tkowej fazy walcowania na gor膮co blach i pr臋t贸w, korzystnych ze wzgl臋du na zamykanie i spajanie wewn臋trznych nieci膮g艂o艣ci materia艂owych we wlewkach z ci膮g艂ego odlewania.A numerical model and selected simulation results of the roughing phase of sheet and bar rolling are presented in the paper. Simulations have been performed for geometric models of continuous ingots with introduced internal material voids. The model and rolling simulation parameters have corresponded to rolling conditions in the LPS rolling line at the Institute for Ferrous Metallurgy. Stress distribution in a roll gap and changes in the voids shape were analysed. Based on the results of simulation, some recommendations have been formulated on selection of process parameters for the roughing phase of sheet and bar rolling, resulting in effective closing and welding of material voids in continuous ingots
Microstructure and Plastic Properties of Mg-Li Alloys Smelted in Vacuum Induction Furnaces after Hot Working
The paper analyses the characteristics of plasticity and microstructure of magnesium alloys with lithium meant for hot plastic working with different lithium content. The alloys were prepared in conditions of vacuum smelting. Achieved ingots were subject to hot extrusion. Tests on Gleeble simulator were conducted to assess the susceptibility of tested alloys to plastic forming in conditions of hot plastic working. For tested alloy the activation energy was marked for hot plastic deformation and plasticity characteristics in function of Zener-Hollomon parameter. After the analysis of the influence of temperature on the deformability of tested alloys it was stated that the alloy containing 8%Li (LAZ831) has better susceptibility to plastic treatment than alloy containing 4%Li (LAZ431), but higher than in case of classic magnesium alloys - AZ31
Wp艂yw odkszta艂cenia w procesie ci膮gnienia i modyfikacji powierzchni na odporno艣膰 na korozj臋 elektrochemiczn膮 drut贸w przeznaczonych dla stomatologii
The study presents the results of research into the impact of strain in cold drawing and surface modification treatment on corrosion properties of wires made of X10CrNi 18-8 steel used in maxillofacial surgery. Scanning microscopy enabled to make images of the surface of wires after drawing process as well as after surface modification treatment. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves in artificial saliva. In order to evaluate physical and chemical properties of the surface, electrochemical impedance spectroscopy was performed.
Test results show deterioration of corrosion properties of wires along with strain taking place in drawing process. It was proved that electrochemical polishing and chemical passivation caused sudden increase of resistance of wires made of stainless steel to pitting corrosion in artificial saliva.W pracy przedstawiono wyniki bada艅 nad wp艂ywem odkszta艂cenia w procesie ci膮gnienia na zimno oraz zabieg贸w modyfikacji powierzchni na w艂a艣ciwo艣ci korozyjne drut贸w wykonanych ze stali X10CrNi 18-8 przeznaczonych do zabieg贸w chirurgii twarzowo - szcz臋kowej. Przy pomocy mikroskopii skaningowej zobrazowano powierzchni臋 drut贸w zar贸wno po procesie ci膮gnienia, jak i po zabiegach obr贸bki powierzchniowej. Odporno艣膰 na korozj臋 elektrochemiczn膮 oceniano na podstawie rejestracji krzywych polaryzacji anodowej w roztworze sztucznej 艣liny. W celu oceny w艂a艣ciwo艣ci fizykochemicznych powierzchni przeprowadzono elektrochemiczn膮 spektroskopi臋 impedancyjn膮.
Wyniki bada艅 wskazuj膮 na pogorszenie w艂a艣ciwo艣ci korozyjnych drut贸w wraz z zachodz膮cym w procesie ci膮gnienia umocnieniem odkszta艂ceniowym. Stwierdzono, 偶e zabiegi elektrochemicznego polerowania i chemicznej pasywacji spowodowa艂y wzrost odporno艣ci drut贸w wykonanych ze stali nierdzewnej na korozj臋 w偶erow膮 w roztworze sztucznej 艣liny
Numerical model of plates and bars rolling in the LPS semi-industrial scale and in industrial conditions
Tematyka modelowania komputerowego procesu walcowania blach i pr臋t贸w jest w chwili obecnej szeroko poruszana w literaturze polskiej i 艣wiatowej. Jest to zwi膮zane z ci膮g艂ym rozwojem metod numerycznych oraz ich znaczenia w przygotowaniu produkcji wyrob贸w walcowanych. Prowadzenie symulacji numerycznych na etapie projektowania procesu walcowania pozwala okre艣li膰 m.in. efekty, jakie zostan膮 uzyskane w materiale po procesie odkszta艂cania, a co za tym idzie, w艂a艣ciwo艣ci wyrobu. W zastosowaniach przemys艂owych pozwala to na obni偶enie koszt贸w planowania produkcji i szybkie dopasowanie profilu produkcji do potrzeb zmieniaj膮cego si臋 rynku. W Instytucie Metalurgii 呕elaza w Gliwicach powsta艂a linia walcownicza LPS, kt贸ra umo偶liwia m.in. eksperymentalne sprawdzenie poprawno艣ci zaprojektowanego procesu walcowania blach i pr臋t贸w z nowych gatunk贸w materia艂贸w. Aby prawid艂owo przewidywa膰 zachowanie si臋 materia艂u w trakcie walcowania, uzyskane efekty strukturalne oraz parametry si艂owe procesu walcowania, badania fizyczne, prowadzone na linii LPS, b臋d膮 wspomagane obliczeniami numerycznymi. Model numeryczny procesu walcowania blach i pr臋t贸w zosta艂 przygotowany w Katedrze Technologii Materia艂贸w Politechniki 艢l膮skiej.The numerical modeling of plate and bar rolling process is now being widely discussed in domestic and foreign literature. This is due to the continuous development of numerical methods and their importance in preparation of rolled products manufacturing. Conducting numerical simulations at the design stage of rolling process allows to specify the effects to be obtained in the material after deformation process, and hence the properties of the product. It allows to reduce the cost of production planning and quickly adjust the production profile to the needs of a changing market. In the Institute for Ferrous Metallurgy, the line for semi-industrial rolling (LPS) has been constructed. It enables the experimental verification of the designed process of rolling plates and bars of new material grades. To correctly predict the material behavior during rolling, the structural effects and force-energy parameters of the process carried out on the LPS line will be supported by numerical simulations. The numerical model of plate and bar rolling process has been prepared in the Department of Materials Technology, Silesian University of Technology, and is presented in this paper
Elaboration of technological recommendations for rolling metal sheets in the LPS on the basis of numerical and physical simulations results
W niniejszym referacie przedstawiono zalecenia technologiczne do walcowania blach i pr臋t贸w w LPS w oparciu o wyniki z symulacji numerycznych i fizycznych, bada艅 dylatometrycznych oraz oblicze艅 w艂asnych w programie "TTSteel" do symulacji obr贸bki cieplnej prowadzonych dla trzech wytypowanych gatunk贸w stali. Wyniki symulacji dla walcowania z zastosowaniem zbijacza zgorzeliny wskazuj膮 na nadmierny spadek temperatury na powierzchni wsadu. Proponowany kontrolowany spos贸b ch艂odzenia dla uzyskania struktury ko艅cowej polega na zastosowaniu r贸偶nych kombinacji odkszta艂cenia plastycznego, szybko艣ci ch艂odzenia, czasowego wytrzymania w sta艂ej temperaturze i ko艅cowego doch艂adzania po zako艅czeniu procesu obr贸bki cieplno-plastycznej. Zak艂ada si臋 r贸wnie偶 mo偶liwo艣膰 wprowadzenia obr贸bki cieplnej w miejsce tych wariant贸w, w kt贸rych istnieje niebezpiecze艅stwo nadmiernych napr臋偶e艅 i odkszta艂ce艅.The paper presents technological recommendations for rolling metal sheets and rods in the LPS line based on results of numerical and physical simulations, dilatometric tests and calculations using "TTSteel" program for simulation of heat treatment conducted for three selected types of steel. The results of simulation with use of the descaler show the excessive drop in temperature on the charge surface. The suggested controlled way of cooling to achieve the final structure is based on the application of various combinations of plastic deformations, cooling rates and holding up at a stable temperature followed by the final sub-cooling after the completion of thermal-mechanical working. It is also assumed that heat treatment operations may be introduced instead of the options where there is a danger of introduction of too large stresses and strains
Thermal Assessment of Modified Ultra-Light Magnesium-Lithium Alloys
The paper presents the results of the influence of commercial TiBor and AlSr10 master alloys on the refine the grains size, hardness and crystallisation process based on the thermal-derivation analysis of light cast magnesium-lithium-aluminium alloys. The effects of TiBor and AlSr10 content on the characteristic parameters of the crystallisation process of Mg-Li-Al alloys were investigated by thermal-derivative analysis (TDA). Microstructural evaluations were identified by light microscope, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy