Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 453

Liczba wyników na stronie
first rewind previous Strona / 23 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  żeliwo sferoidalne
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 23 next fast forward last
EN
Nodular cast irons are used in a wide range of industrial applications, especially in the automotive industry. SiMo-type of nodular cast iron is suitable for high-temperature applications, for example the exhaust manifolds of the combustion engines; SiCu-type of nodular cast iron is used in various components of tribotechnical units. These automotive components often work in a corrosive environment. Therefore, the aim of this paper is to compare the corrosion resistance of two types of the nodular cast irons (SiMo-type and SiCu-type). Corrosion resistance was determined by the exposure immersion test at ambient temperature. Specimens of both types of nodular cast iron were immersed in 3.5 % NaCl solution (to simulate sea water) and gradually removed from the solution after 1, 2, 4 and 8 weeks. Subsequently, the weight loss (g) and the average corrosion rate (g m-2 day-1) were calculated. Experimental results show that nodular cast iron alloyed by Si and Mo has higher corrosion resistance than the nodular cast iron alloyed with Si and Cu. Moreover, the mechanical properties (evaluated by tensile test, impact bending test and hardness test) and fatigue properties of both types of nodular cast iron has been compared in the paper.
EN
In this work the analysis of corrosion for ductile iron pipes with diameters of 350 and 500 mm was performed. Two phenomena regarding the pipes coating deterioration have been recognized: corrosion and abrasion. The corrosion tests performed on different coatings in a neutral salt spray for up to 1000 hours indicate that this method is applicable for a rough external surface of centrifugally casted ductile iron pipes. The abrasion tests have been performed manually, using a grinding paper 1000#, due to an irregular profile of the external pipe surface transferred from the casting mold. It helped to obtain “spotted” sections, which were further microscopically analyzed (layer-by-layer). The last procedure, however not standardized, could be in some regards more convenient comparing to traditional cross-sections.
PL
W pracy dokonano analizy korozji rur z żeliwa sferoidalnego o średnicach 350 i 500 mm. Wykryto dwa zjawiska związane z pogorszeniem się powłoki rur: korozja i ścieranie. Testy korozyjne przeprowadzone na różnych powłokach w neutralnej mgle solnej przez okres do 1000 godzin wskazują, że metoda ta ma zastosowanie do szorstkiej zewnętrznej powierzchni odlewanych wirowo rur z żeliwa sferoidalnego. Testy na ścieranie przeprowadzono ręcznie przy użyciu papieru ściernego 1000 #, ze względu na nieregularny profil zewnętrznej powierzchni rury przeniesionej z formy odlewniczej. Pomogło to w uzyskaniu „plamkowych” przekrojów, które poddano dalszej analizie mikroskopowej (warstwa po warstwie). Ostatnia procedura, choć nie znormalizowana, może być pod pewnymi względami wygodniejsza w porównaniu do tradycyjnych przekrojów poprzecznych.
EN
This paper presents the problems related to smelting gray and ductile cast iron. Special attention is paid to the metallurgical quality of cast iron. It depends on the type of furnace, charge materials and the special combination of charge, overheating and holding temperature, melting time, modification and spheroidization method. The evaluation of metallurgical quality has been performed by using derivative-thermal analysis (DTA). During the smelting process and secondary metallurgy, the ITACA system was used allowing to obtain information on alloy characteristic temperatures (Tliquidus, TeMin, TeMax, Tsolidus), VPS value, recalescence value, IGQ coefficient, nucleation gauge, porosity etc. The results of investigations and calculations are displayed in the form of graphs and dependencies. It has been shown that the derivative-thermal analysis (DTA) is an effective complement of chemical analysis and it has been found that both the increase in temperature and metal holding time have a negative impact on the metallurgical quality of liquid metal. The metallurgical quality can be improved by using proper composition of charge materials and modifiers.
EN
The article presents research on solid particle erosive wear resistance of ductile cast iron after laser surface melting. This surface treatment technology enables improvement of wear resistance of ductile cast iron surface. For the test ductile cast iron EN GJS-350-22 surface was processed by high power diode laser HPDL Rofin Sinar DL020. For the research single pass and multi pass laser melted surface layers were made. The macrostructure and microstructure of multi pass surface layers were analysed. The Vickers microhardness tests were proceeded for single pass and multi pass surface layers. The solid particle erosive test according to standard ASTM G76 – 04 with 30°, 60° and 90° impact angle was made for each multi pass surface layer. As a reference material in erosive test, base material EN GJS-350-22 was used. After the erosive test, worn surfaces observations were carried out on the Scanning Electron Microscope. Laser surface melting process of tested ductile cast iron resulted in maximum 3.7 times hardness increase caused by microstructure change. This caused the increase of erosive resistance in comparison to the base material.
EN
This article is a description of the progress of research and development in the area of massive large-scale castings - slag ladles implemented in cooperation with the Faculty of Foundry Engineering of UST in Krakow. Slag ladles are the one of the major castings that has been developed by the Krakodlew (massive castings foundry) for many years. Quality requirements are constantly increasing in relation to the slag ladles. Slag ladles are an integral tool in the logistics of enterprises in the metallurgical industry in the process of well-organized slag management and other by-products and input materials. The need to increase the volume of slag ladles is still growing. Metallurgical production is expected to be achieved in Poland by 2022 at the level of 9.4 million Mg/year for the baseline scenario - 2016 - 9 million Mg/year. This article describes the research work carried out to date in the field of technology for the production of massive slag ladles of ductile cast iron and cast steel.
EN
In the present work, different Cu-alloyed model ductile irons with ferritic (0%Cu-0.09%Mn), mixed ferritic-pearlitic (0.38%Cu-0.40%Mn) and pearlitic (0.69%Cu-0.63%Mn) microstructure were produced and analyzed in terms of their electrochemical corrosion behavior in a 3.5wt.%NaCl aqueous solution containing naturally dissolved oxygen at room temperature (25°C). The remaining elements such as Si and Mg were kept at balanced levels in an attempt to minimize variations in graphite size and distribution among different samples. The corrosion resistance was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization. Microstructure analysis of the cast alloys confirmed similarity in the graphite morphology among the different cast samples and the expected variations in the metallic matrix. In the absence of passivation, it was found that the addition of copper led to an increase in corrosion resistance, which could be attested by higher values polarization resistance and corrosion potential.
EN
The study presented in this paper concerned the possibility to apply a heat treatment process to ductile cast-iron thin-walled castings in order to remove excessive quantities of pearlite and eutectic cementite precipitates and thus meet the customer’s requirements. After determining the rates of heating a casting up to and cooling down from 900°C feasible in the used production heat treatment furnace (vh = 300°C/h and vc = 200°C/h, respectively), dilatometric tests were carried out to evaluate temperatures Tgr, TAc1 start, TAc1 , TAr1 start, and TAr1 end. The newly acquired knowledge was the base on which conditions for a single-step ferritizing heat treatment securing disintegration of pearlite were developed as well as those of a two-step ferritization process guaranteeing complete disintegration of cementite and arriving at the required ferrite and pearlite content. A purely ferritic matrix and hardness of 119 HB was secured by the treatment scheme: 920°C for 2 hours / vc = 60°C/h / 720°C for 4 hours. A matrix containing 20–45% of pearlite and hardness of 180–182 HB was obtained by applying: 920°C for 2 hours or 4 hours / vc = 200°C/h to 650°C / ambient air.
EN
An investigation was conducted to determine the role of Co particles in the WC-Co coating produced with the High Velocity Oxygen-Fuel (HVOF) spraying on microstructure, mechanical and wear properties in a system of type: WC-Co coating/ductlile cast iron. The microstructure of the thermal sprayed WC-Co+Co coating was characterized by scanning electron (SEM) and transmission electron (TEM) microscopes as well as the analysis of chemical and phase composition in microareas (EDS, XRD). For analysis of the quality and adhesion of coatings, the scratch-test was applied. It was found that as a result of the HVOF spray of WC-Co powders with the addition of Co particles, the coatings of low porosity, high hardness, a very good adhesion to the substrate, compact structure with partially molten Co particles and finely fragmented WC particles embedded in a cobalt matrix, coming to the size of nanocrystalline sizes were obtained. Moreover, the results were discussed in reference to examination of bending strength considering cracking and delamination in the system of (WC-Co+Co)/ductile cast iron as well as hardness and wear resistance of the coating. It was found that the addition of Co particles was significantly increase resistance to cracking and wear behaviour in the studied system.
PL
W pracy przedstawiono wyniki badań, dotyczące wpływu modyfikacji składu chemicznego powłok WC-Co (poprzez domieszkowanie cząstkami Co), wytworzonych techniką natryskiwania proszkowego naddźwiękowego z dużymi prędkościami (HVOF) na mikrostrukturę, właściwości mechaniczne i użytkowe układu typu: powłoka WC-Co/żeliwo sferoidalne. Mikrostruktura powłok WC-Co+Co była analizowana za pomocą mikroskopu świetlnego, skaningowego i transmisyjnego wraz z przeprowadzeniem badań składu chemicznego i fazowego powłok w mikroobszarach przy wykorzystaniu techniki EOS i XRO. Do analizy jakości i przyczepności powłok zastosowano test zarysowania. Stwierdzono, że w wyniku natryskiwania techniką HVOF proszków WC-Co z dodatkiem cząstek Co, powłoki charakteryzują się niską porowatością wysoką twardością bardzo dobrą przyczepnością do podłoża, zwartą budową z częściowo stopionymi cząstkami Co i silnie rozdrobnionymi cząstkami WC osadzonymi w kobaltowej matrycy, dochodzącymi do wymiarów nanometrycznych. Ponadto w pracy przedstawiono wyniki dotyczące wytrzymałości na zginanie układu WC-Co+Co/żeliwo sferoidalne w zestawieniu z analizą pękania i delaminacji powłoki w obszarze granicy rozdziału, oraz wynikami pomiarów twardości i odporności na zużycie powłoki. Stwierdzono, że dodatek cząstek Co znacznie zwiększa odporność na pękanie i zużycie w badanym układzie.
EN
The article presents results of the research on laser alloying of the ductile cast iron EN-GJS 350-22 substrate with the mixture of titanium powder with addition of 5 wt.% of tungsten. The aim of the process was to obtain surface layer with the in-situ composite structure. Laser alloying process was carried out using high power diode laser (HPDDL) with rectangular laser beam focus and uniform power density distribution in one axis of the beam focus (top-hat profile). The tests included determination of the influence of process parameters on the dimensions of the alloyed beads, metallographic macroscopic and microscopic observations, microhardness measurements of the laser alloyed layers and EDS chemical composition tests.
PL
Artykuł przedstawia wyniki badań nad stopowaniem laserowym żeliwa sferoidalnego EN-GJS 350-22 mieszaniną proszku tytanu z dodatkiem 5 %wag. wolframu. Celem procesu było uzyskanie warstwy wierzchniej o strukturze kompozytowej metodą in-situ. Proces stopowania przeprowadzony został z wykorzystaniem lasera diodowego dużej mocy HPDDL o ognisku prostokątnym i równomiernym rozkładzie gęstości mocy w jednej osi ogniska (top-hat profile). Badania obejmowały określenie wpływu parametrów procesu na wymiary ściegów stopowanych, obserwacje makroskopowe i mikroskopowe, pomiary mikrotwardości uzyskanych warstw wierzchnich oraz badania składu chemicznego EDS.
PL
W niniejszym artykule przedstawiono system wodociągowy, który służy do zaopatrywania w wodę mieszkańców oraz zakładów produkcyjnych w jednostkach osadniczych. Opisano także zalety i wady materiałów dotychczas stosowanych do budowy sieci wodociągowych. Przedstawiono również innowacyjny system rur BLUTOP z żeliwa sferoidalnego dedykowany dla systemów wodociągowych o małym zakresie średnic.
EN
This article presents a water supply system that is used to supply residents in settlement units and production plants in water. The advantages and disadvantages of materials used in the construction of water supply networks have also been described. Also presented is an innovative system of BLUTOP pipes made of ductile iron dedicated for water systems with a small diameter range.
EN
In recent years, the research of nodular cast iron has been focused on increasing fatigue resistence. In the paper, two types of alloyed nodular cast irons have been investigated – SiMo-nodular cast iron alloyed by 4% of silicon and 1% of molybdenum and SiCu-nodular cast iron alloyed by 4% of silicon and 1.5% of copper. SiMo-nodular cast iron is suitable for high-temperature applications, for example the exhaust manifolds of the combustion engines. SiCu-nodular cast iron is used in various components of tribotechnical units. These components are often loaded by fatigue. The mechanical and fatigue behaviour of both nodular cast iron types has been studied by means of tensile test, impact bending test, hardness test and fatigue tests. Fatigue tests were realised at low frequency cyclic push-pull loading up to 10 million cycles. The relationship between the amplitude of stress and number of cycles to failure was investigated and the fatigue strength was determined. Mechanical and fatigue properties of both nodular cast iron types are correlated with the microstructure of specimens.
PL
Odlewy z żeliwa sferoidalnego znajdują szerokie zastosowanie w wielu gałęziach przemysłu ze względu na swoje właściwości mechaniczne. Wytwarzanie tego gatunku materiału wymaga utrzymania reżimu technologicznego oraz czystości materiału wyjściowego. Z tego powodu stale rozwijane są metody wytwarzania oraz kontroli tego materiału. W niniejszej publikacji przedstawiona została nowa metoda sferoidyzacji i modyfikacji żeliwa w formie. Innowacją tej metody jest zastosowanie specjalnie opracowanej konstrukcji komory, w której zachodzi reakcja uszlachetniania żeliwa. W artykule przedstawione zostały przeprowadzone badania symulacyjne, mające na celu analizę profilu przepływającego ciekłego metalu w zadanej konstrukcji. Następnie wprowadzone zostały zmiany geometrii komory, celem optymalizacji jej kształtu oraz powtórnie wykonano analizę w tożsamych warunkach brzegowych. Wynikiem badań jest opracowanie konstrukcji, która zapewni odpowiedni charakter przepływu pozwalający na uzyskanie dobrej jakości żeliwa i odlewów z żeliwa sferoidalnego w formie odlewniczej.
EN
Ductile iron castings are widely used in many industrial branches because of their mechanical properties. The production process of such a grade of cast iron requires the maintenance of the technological regime and the purity of initial charge material. For this reason, methods of manufacturing and controlling materials are constantly being developed. This publication presents a new method of modification and spheroidization in the mould. The innovation of this method is the use of specially developed construction of the reaction chamber. Simulation studies were conducted to analyze the flow profile of liquid metal in the developed shapes of the chamber. Subsequently, the changes in the geometry of the chamber were made and analyzed under the same boundary conditions. The result of the study is the designation of a structure that will provide the appropriate flow characteristics to achieve good quality castings.
EN
The results of experimental investigations influence of vibratory shot peening on surface roughness and residual stress of spheroidal graphite cast iron objects were presented. The surfaces before vibratory shot peening were milled using different feed. After vibratory shot peening surface roughness Ra = 0.7÷0.9 μm was obtained and in surface layer compressive residual stress, with the maximum (absolute) value from 170 MPa to 330 MPa at a depth 0.4÷0.7 mm have been formed. For accepted vibratory shot peening condition it was recommended to use time of about 8 minutes.
PL
Przedstawiono wyniki badania wpływu czasu nagniatania wibracyjnego elementów z żeliwa sferoidalnego na chropowatość powierzchni i rozkład naprężeń własnych w warstwie wierzchniej nagniatanych przedmiotów. Powierzchnie przewidziane do nagniatania frezowano z posuwem o różnej wartości. W wyniku nagniatania uzyskano chropowatość powierzchni w granicach Ra = 0,7÷0,9 μm, a w warstwie wierzchniej ukształtowano ściskające naprężenia własne o maksymalnej (bezwzględnej) wartości od 170 MPa do 330 MPa na głębokości 0,4÷0,7 mm. Dla przyjętych warunków nagniatania zalecono stosowanie czasu nagniatania ok. 8 min.
15
Content available remote Influence of changes in machinability of nodular cast iron on manufacturing costs
EN
Attempts to explain changes in the efficiency of nodular cast iron machining caused by the dispersion of its mechanical properties affecting on the intensity of tools wear (such as VHM drills) have been presented. It has been also assessed to what extent changes in mechanical properties of tools, within the limits of the standards, can change the machining efficiency in quite intensive machining conditions of the automotive industry.
PL
Podjęto próbę wyjaśnienia zmian efektywności obróbki żeliwa sferoidalnego; było to spowodowane rozrzutem jego właściwości mechanicznych, odbijającym się na intensywności zużywania się narzędzi (w tym wypadku wierteł z węglików spiekanych). Oceniono, na ile zmiany właściwości mechanicznych narzędzi – mieszczące się w granicach norm – mogą wpływać na efektywność obróbki w dość intensywnych warunkach skrawania w przemyśle motoryzacyjnym.
16
Content available remote Bezwykopowa budowa wodociągów w Bydgoszczy i Gdańsku
PL
Bezwykopowa budowa podziemnej infrastruktury, choć nadal niejednokrotnie wzbudza duże zainteresowanie osób spoza branży, staje się normą, szczególnie, jeśli prace budowlane trzeba przeprowadzić w terenach o gęstej zabudowie, pod ciągami komunikacyjnymi czy przeszkodami naturalnymi. Tak też było w Bydgoszczy i Gdańsku, gdzie do budowy wodociągów zastosowano metodę horyzontalnych przewiertów sterowanych i zainstalowano rury z żeliwa sferoidalnego.
EN
The present article discusses the process of optimizing the structure of artificial neural networks applied in modelling the wear of spheroidal graphite cast iron (SG cast iron). The networks were trained using the RPROP gradient method with the application of the SNNS package supported by original self-developed software, which enabled automatic creation, training and testing of networks with different sizes of hidden layers. Based on the results of an analysis of learning process and testing a package of 625 networks, the network was selected which – when modelling the process of spheroidal cast iron wear – generates the slightest errors during testing.
PL
W pracy przedstawiono proces optymalizacji struktury sztucznych sieci neuronowych użytych do modelowania zużycia żeliwa sferoidalnego. Sieci uczono metodą gradientową RPROP przy użyciu pakietu SNNS wspomaganego autorskim oprogramowaniem, które umożliwiało automatyczne tworzenie, uczenie i testowanie sieci o różnych wielkości warstw ukrytych. Na podstawie analizy wyników procesu uczenia i testowania pakietu 625 sieci dobrano tę, która modelując proces zużycia żeliwa sferoidalnego generuje najmniejsze błędy podczas testowania.
EN
The goal of this article is non-destructive ultrasonic testing of internal castings defects. Our task was to cast several samples with defects like porosity and cavities (where belongs mostly shrinkages) and then pass these samples under ultrasonic testing. The characteristics of ultrasonic control of castings are presented in the theoretical part of this article. Ultrasonic control is a volume non-destructive method that can detect internal defects in controlled materials without damaging the construction. It is one of the most widely used methods of volume non-destructive testing. For experimental control were made several cylindrical samples from ferritic grey and ductile cast iron. Because of the form and dispersion of graphite of grey cast iron it was not possible to make ultrasonic records on this casting with probe we used, so we worked only with ductile cast iron. Ultrasonic records of casting control are shown and described in the experimental part. The evaluation of the measurement results and the reliability of the ultrasonic method in castings control is listed at the end of this article.
EN
The excellent property combination of thin wall ductile iron castings (TWDI), including thin wall alloyed cast iron (e.g. austenitic TWDI) has opened new horizons for cast iron to replace steel castings and forgings in many engineering applications with considerable cost benefits. TWDI is considered as a potential material for the preparation of light castings with good mechanical and utility properties, the cost of which is relatively low. In this study, unalloyed and high Ni-alloyed (25% Ni) spheroidal graphite cast iron, with an austenitic metallic matrix were investigated. The research was conducted for thin-walled iron castings with 2, 3 and 5mm wall thickness, using different mould temperature (20°C, and 160°C) to achieve various cooling rates. The metallographic examinations i.e. characteristic of graphite nodules, metallic matrix, and primary grains of austenite dendrites (in high-nickel NTWDI) and mechanical properties were investigated. The study shows that homogeneity of the casting structure of thin-walled castings varies when changing the wall thickness and mould temperature. Finally, mechanical properties of thin-walled ductile iron castings with ferritic-pearlitic and austenitic metallic matrix have been shown.
EN
The paper presents the initial results of investigation concerning the abrasion resistance of cast iron with nodular, vermicular, or flake graphite. The nodular and vermicular cast iron specimens were cut out of test coupons of the IIb type with the wall thickness equal to 25 mm, while the specimens made of grey cast iron containing flake graphite were cut out either of special casts with 20 mm thick walls or of the original brake disk. The abrasion tests were carried out by means of the T-01M tribological unit working in the pin-on-disk configuration. The counterface specimens (i.e. the disks) were made of the JT6500 brand name friction material. Each specimen was abraded over a distance of 4000 m. The mass losses, both of the specimens and of the counterface disks, were determined by weighting. It was found that the least wear among the examined materials was exhibited by the nodular cast iron. In turn, the smallest abrasion resistance was found in vermicular cast iron and in cast iron containing flake graphite coming from the brake disk. However, while the three types of specimens (those taken from the nodular cast iron and from grey cast iron coming either from the special casts or from the brake disk) have almost purely pearlitic matrix (P95/Fe05), the vermicular cast iron matrix was composed of pearlite and ferrite occurring in the amounts of about 50% each (P50/Fe50). Additionally, it was found that the highest temperature at the cast iron/counterface disk contact point was reached during the tests held for the nodular cast iron, while the lowest one occurred for the case of specially cast grey iron.
first rewind previous Strona / 23 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.