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EN
Tensile deformation behavior of nuclear grade Austenitic Stainless Steel (SS) and its welded joints fabricated by Gas Tungsten Arc Welding (GTAW) and Activated Flux Gas Tungsten Arc Welding (AGTAW) processes were studied and correlated with relevant microstructural morphologies using Infrared Thermography (IRT) technique. The microstructure of base metal showed a complete austenite phase. GTAW Fusion Zone (FZ) exhibited both primary ferrite and primary austenite mode of solidification. Meantime, AGTAW FZ exhibited only primary austenite mode of solidification. A strain rate of 4.4x10-4 s-1 was used during the tensile test of the base metal and welded joints. The failure locations of the base metal, GTAW and AGTAW samples were noticed at the center of the gauge portion, the base metal side away from Fusion Line (FL) and Heat Affected Zone (HAZ) respectively. The temperature variations of the base metal and weld zones were recorded in the form of thermograms using the IR camera at the different stages of the tensile deformation. During deformation study, peak temperature of 39.2 °C, 38.8 °C and 34 °C were observed at the base metal, GTAW and AGTAW samples respectively. The lesser peak temperature of the AGTAW sample compared to the base metal and GTAW samples indicated that the AGTAW sample undergone lesser deformation. Moreover, tensile deformation behaviours of the base metal and welded joints were correlated with their microstructural morphologies using corresponding temperature curves.
PL
W pracy zbadano zachowanie deformacji podczas rozciągania austenitycznej stali nierdzewnej i jej połączeń spawanych wykonanych metodą GTAW (Gas Tungsten Arc Welding) oraz AGTAW (Activated Flux Gas Tungsten Arc Welding), a następnie skorelowano je z odpowiednimi morfologiami mikrostrukturalnymi za pomocą termografii w podczerwieni (ang. lnfrared Thermography). Mikrostruktura materiału bazowego wykazała całkowitą fazę austenitu. Spoina GTAW wykazywała zarówno ferryt, jak i austenit, podczas gdy spoina AGTAW wykazywała jedynie austenit. Podczas próby rozciągania materiału bazowego i złączy spawanych zastosowano prędkość odkształcania o wartości 4,4x10-4 s-1. Do zerwania poszczególnych próbek doszło odpowiednio na środku próbki materiału bazowego, w linii wtopienia złącza spawanego GTAW i w strefie wpływu ciepła (SWC) złącza spawanego AGTAW. Zmiany temperatury w materiale rodzimym i poszczególnych obszarach złączy spawanych rejestrowano w formie termogramów za pomocą kamery na podczerwień, przy różnych etapach deformacji podczas rozciągania. Podczas badań odkształceń zaobserwowano maksymalne wartości temperatury: 39,2 °C, 38,8 °C i 34 °C odpowiednio w próbkach z materiału bazowego, spawanych GTAW i spawanych AGTAW. Niższa maksymalna temperatura próbki spawanej metodą AGTAW w porównaniu z pozostałymi próbkami wskazała, że uległa ona mniejszemu odkształceniu. Ponadto zachowania deformacji przy rozciąganiu materiału rodzimego i złączy spawanych zostały skorelowane z obrazami ich mikrostruktur przy użyciu odpowiednich krzywych temperatur.
EN
In the present paper, elemental Fe, Cr and Ni powders were used to fabricate nano-structured duplex and ferritic stainless steel powders by using high energy planetary ball milling. We have studied the effect of milling atmosphere like wet (toluene) and dry (argon) milling of elemental Fe-18Cr-13Ni (duplex) and Fe-17Cr-1Ni (ferritic) powders for 10 h in a dual drive planetary mill. Stearic acid of 1wt.% was added during milling to avoid agglomeration. The dry and wet milled duplex and ferritic stainless steel powders were characterized by XRD, SEM and particle size analysis techniques. We have found that both the milling atmospheres have great influence in controlling the final particle morphology, size and phase evolution during milling. It was reported that dry milling is more effective in reducing particle size than the wet milling. The Nelson-Riley method of extrapolation was used to calculate the precise lattice parameter and Williamson-Hall method was used to calculate the crystallite size and lattice strain of both the stainless steel milled in argon atmosphere. Dry milled duplex and ferritic stainless steel were then consolidated by conventional sintering method at 1100, 1200 and 1300°C temperatures under argon atmosphere for 1 hour.
EN
The article presents a computational model build with the use of artificial neural networks optimized by genetic algorithm. This model was used to research and prediction of the impact of chemical elements and heat treatment conditions on the mechanical properties of ferrite stainless steel. Optimization has allowed the development of artificial neural networks, which showed a better or comparable prediction result in comparison to un-optimized networks has reduced the number of input variables and has accelerated the calculation speed. The introduced computational model can be applied in industry to reduce the manufacturing costs of materials. It can also simplify material selection when an engineer must properly choose the chemical elements and adequate plastic and/or heat treatment of stainless steels with required mechanical properties.
EN
Crystal structure and phase composition of stainless steel substrates (AISI 304 type) was studied and it was found that they adopted the cubic symmetry. The calculated elementary cell parameter for the mayor Fe-Ni phase (weight fraction 99%) was a = 3.593 Å, whereas the mean grain size was = 2932 Å. Morphology of the stainless steel substrate surface was studied with profilometry. Mechanical properties of the stainless steel substrates and stainless steel substrates coated with ceramic layer of barium strontium titanate were studied with microhardness tester. For measurements performed according to the Vickers method the average microhardness was found HV = 189 or HV = 186 for the “in-line” and “mapping” measurement pattern, respectively. The sol-gel method was used to coat the surface of the stainless steel substrate with a thin ceramic layer of the chemical composition Ba0.6 Sr0.4 TiO3 . It was found that the stainless steel substrate covered with sol-gel deposited ceramic coating exhibited the average hardness within the range HV = 217 up to HV = 235 for loading force F = 98 mN and F = 0.98 N, respectively. The Knopp method was also used and it was found that the stainless steel substrate with Ba0.6 Sr0.4 TiO3 coating exhibited hardness HK = 386.
EN
The article describes the effect of alloyed additives in base material and filler metal on intergranular corrosion. Steel 1.2 mm thick, titanium-stabilized ferritic stainless steel and titanium and niobium-stabilized ferritic stainless steel have been surfacing method MAG (135). The specimens received was subjected to macro and microscopic tests, hardness tests and the intergranular corrosion resistance test. The study showed a higher corrosion resistance of niobium and titanium stabilized steel from titanium-stabilized steel. In addition, a ferritic fine-grain structure was found in the padding axis made with the use of filler metal with titanium and niobium microadditives.
PL
W artykule opisano wpływ dodatków stopowych w materiale rodzimym i spoiwie na korozje międzykrystaliczną. Blachy o grubości 1,2 mm ze stali nierdzewnej ferrytycznej stabilizowanej tytanem oraz stali nierdzewnej ferrytycznej stabilizowanej tytanem i niobem zostały napawane metodą MAG (135). Otrzymane próbki poddano badaniom makro i mikroskopowym, zmierzono twardość oraz przeprowadzono badania odporności na korozje międzykrystaliczną. W wyniku przeprowadzonych badań stwierdzono wyższą odporność korozyjną stali stabilizowanej niobem i tytanem od stali stabilizowanej tylko tytanem. Ponadto, wykazano występowanie struktury drobnoziarnistej ferrytycznej w osi napoiny wykonanej przy użyciu materiału dodatkowego z mikrododatkami tytanu i niobu.
EN
The article presents the procedure for qualifying brazing technology in a vacuum furnace on the example of stainless steel elements joined with copper filler material from the F-No group. 105, in accordance with the ASME Sec. IX, part QB (ASME Boiler and Pressure Vessel Code. Qualification Standard for Welding, Brazing and Fusing; Procedures; Welders; Brazers; and Welding, Brazing and Fusing Operators). The essential variables of the furnace brazing process are discussed in relation to the requirements of the protocol of qualified PQR (Procedure Qualification Record) and BPS (Brazing Procedure Specification) in accordance with the ASME Sec. IX. The requirements for joints by the calculation code ASME Sec. VIII div.1 (Rules of Construction of Pressure Vessels), related to the working temperature of the designed device have also been taken into account. The paper presents examples of brazed joints made and their properties (strength, fill level of the clearance) obtained on the basis of the carried out tests. Attention was paid to the technological aspects during the performance of brazed joints using vacuum furnaces.
PL
W artykule przedstawiono procedurę kwalifikowania technologii lutowania twardego w piecu próżniowym na przykładzie elementów ze stali wysokostopowej nierdzewnej austenitycznej łączonych lutem miedzianym z grupy F-No. 105, zgodnie z przepisami ASME Sec. IX, part QB (ASME Boiler and Pressure Vessel Code. Qualification Standard for Welding, Brazing and Fusing; Procedures; Welders; Brazers; and Welding, Brazing and Fusing Operators). Omówiono zmienne zasadnicze procesu lutowania próżniowego w odniesieniu do wymagań stawianych dokumentacji tj.: protokołowi z kwalifikowanej technologii lutowania PQR (ang. Procedure Qualification Record) oraz Instrukcji technologicznej lutowania BPS (ang. Brazing Procedure Specification) zgodnie z przepisami ASME Sec. IX. Uwzględniono również wymagania stawiane połączeniom przez kod obliczeniowy ASME Sec. VIII div.1 (ang. Rules of Construction of Pressure Vessels), a związane z temperaturą pracy projektowanego urządzenia. Przedstawiono przykłady wykonanych połączeń lutowanych oraz ich właściwości (wytrzymałościowe, stopień wypełnienia szczeliny lutowniczej) uzyskane na podstawie przeprowadzonych badań. Zwrócono uwagę na aspekty technologiczne podczas wykonywania złączy lutowanych przy zastosowaniu pieców próżniowych.
EN
Results of study on the laser welding process of pillow plates heat exchangers are presented in the article. The influence of basic parameters of CO2 laser welding on the quality of overlap joints of AISI 304 stainless steel plates 2.0 and 4.0 mm thick was determined. The range of optimal parameters of welding, providing the highest quality and high mechanical performance of the test joints was determined. The technological conditions elaborated during the study were applied for manufacturing of the real pillow plates heat exchangers with dimensions of 1.5x1.5 m.
PL
W artykule przedstawiono wyniki badań procesu spawania laserowego złączy panelowych wymienników ciepła. Określono wpływ podstawowych parametrów spawania laserem gazowym CO2 na jakość złączy zakładkowych blach ze stali austenitycznej AISI 304 o grubości 2,0 i 4,0 mm. Określono zakres optymalnych parametrów spawania zapewniających najwyższą jakość i wysoką wytrzymałość złączy. Opracowane warunki technologiczne spawania laserowego zastosowano do wytwarzania partii panelowych wymienników ciepła o wymiarach 1,5x1,5 m.
EN
Austenitic stainless steels are often used for a materials in the construction of machines and equipment for agricultural and for industrial construction. One of the most important factors constructional material is corrosion resistance. Equipment with austenitic stainless steel can be easy join by quickly welding at a not to high construction price, but one with the serious problem in aggressive environment is their corrosion resistance. A few corrosion processes in crevices and awkward corners can be avoided at the design stage (low roughness parameters, round-section and other). But still the construction material is exposed to corrosion. These steels often come into contact with an aggressive environment based on nitric acid. The main aim of this research is to investigate corrosion resistance in different time (48, 96, 144, 192, 240, 288, 336 hours). For this used weight loss of test samples and its profile roughness. The research was conducted on austenitic stainless steel in grade in Nitrate acid at 333 K. Corrosion tests confirmed that the research this steel in 65% nitrate acid as a corrosive environments is characterized through proportionate to time corrosion process whose measure may be surface roughness. In industrial practice roughness parameters for all the research times can be used for determine the stage and size of steel corrosion.
PL
Stale nierdzewne są odporne na korozję dzięki zdolności do pasywacji, czyli wytwarzania na powierzchni cienkiej warstewki posiadającej grubość tysięcznych części mikrometra. W porównaniu do zawartości w stali warstewka posiada zwiększoną zawartość chromu, molibdenu i niklu w postaci tlenków. Wytworzona w warunkach naturalnych warstewka pasywna ulega lokalnym uszkodzeniom i zanieczyszczeniom podczas etapów formowania konstrukcji, takich jak spawanie, szlifowanie, lub obróbka termiczna. W miejscach uszkodzonych lub pokrytych zanieczyszczeniami lub rdzą warstewka tlenków metali jest niekompletna, niejednorodna, lub niezdolna do regeneracji. Wytworzenie prawidłowej warstewki tlenków prowadzące do odporności korozyjnej zapewnia proces trawienia i pasywacji. Dobór technologii trawienia i pasywacji zależy przede wszystkim od rodzaju konstrukcji, oraz gatunku stali nierdzewnej. Specjalistyczne przedsiębiorstwa wykonują pasywację w swoich zakładach oraz w terenie. W obu przypadkach stosuje się te same preparaty, przy czym aktualne technologie umożliwiają przeprowadzenie podstawowego procesu trawienia i pasywacji jednocześnie, w postaci jednego etapu. Po procesie wymagane jest dokładne usunięcie chemikaliów oraz bardzo często osuszenie elementów lub konstrukcji. Kontrola powierzchni stali po pasywacji polega na oznaczaniu potencjałów elektrochemicznych oraz sprawdzeniu nieobecności zanieczyszczeń na powierzchni stali nierdzewnej. Dla utrzymania odporności korozyjnej proces trawienia i pasywacji należy powtórzyć w przypadku trwałego skażenia powierzchni stali podczas eksploatacji.
EN
Stainless steels are corrosion resistant due to their ability to passivation which means formation of a thin film, containing increased concentration of chromium, molybdenum and nickel oxides, having thickness of thousands of a micrometer. Naturally occurring passive film is sensitive to local contaminations and defects during construction processes, like welding, grinding and other mechanical treatments. The film of metal oxides is uncompleted, no uniform and unable to be regenerated at the places of damages, or is covered with contaminations or rust. Formation of a proper oxide film that guarantees corrosion resistance can be obtained after pickling and passivation process. The technology applied depends mainly on the type of construction and properties of the stainless steel. Specializing companies perform passivation at their premises or/and in the field. At both cases the same chemicals are applied and presently used technologies allow to perform pickling and passivation process as one step. After the process the chemicals must be precisely removed from the metal surface and elements or constructions might be blown dried. Passivation effects are confirmed by electrochemical potential measurements and by testing of absence of contaminations at the stainless steel surface. The pickling/passivation process should be conducted always in any serious case of stainless steel contamination during exploitation.
PL
Austenityczne stale chromowo-niklowe 304 (1.4301) i 304L (1.4306 oraz 1.4307) od wielu lat są wykorzystywane do budowy urządzeń technologicznych instalowanych na oczyszczalniach ścieków, przepompowniach i zakładach uzdatniania wody. Stale te mogą ulegać korozji w środowisku wodnym z dużą zawartością siarkowodoru oraz okresowo podwyższoną zawartością chlorków. Przykładem szybko postępujących zniszczeń jest opisana w pracy korozja sitopiaskownika, który po 2 latach eksploatacji odznaczał się perforacjami na pokrywach oraz w górnej części ponad poziomem ścieków. Przeprowadzone badania mikroskopowe potwierdziły obecność żywych komórek bakterii i grzybów na ściankach sitopiaskownika. Metoda fluorescencyjnej hybrydyzacji in situ (FISH) wykazała obecność bakterii z klasy γ- i δ-proteobacteria oraz bakterii siarkowych (Acidithiobacillus thiooxidans) należących do klasy γ-proteobacteria. Badania wskazały, że największa intensywność korozji miała miejsce w częściach sitopiaskownika narażonych na działanie wilgotnego powietrza zanieczyszczonego siarkowodorem.
EN
Austenitic chromium-nickel steels 304 (1.4301) and 304L (1.4306 and 1.4307) have been used for many years to build technological devices in water and sewage treatment plants or pumping stations. These steels can be corrosive in aqueous environments with a high content of hydrogen sulphide and periodically increased chloride concentrations. The paper describes an example of fast-progressing corrosive damage of a screenings and grit separator, which after 2 years of operation perforations on the covers and in the part of wall above the sewage level. Microscopic observations confirmed the presence of living cells of bacteria and fungi on the walls of the screenings and grit separator. The fluorescent in situ hybridization (FISH) method showed the presence of sulfur bacteria (Acidithiobacillus thiooxidans) and bacteriafrom the γ- and δ-proteobacteria class. Studies have shown that the highest intensity of corrosion occurred in the parts of the screenings and grit separator exposed to humid air contaminated with hydrogen sulphide.
PL
W artykule przedstawiono zakres prac prowadzonych w Zakładzie Tłoczenia Sieci Badawczej Łukasiewicz – Instytutu Obróbki Plastycznej na przełomie ostatnich lat. Zamieszczono wyniki badań, m.in. prac statutowych, związanych z wyoblaniem wyrobów osiowo niesymetrycznych na specjalnej do tego celu zaprojektowanej przez Zakład Tłoczenia wyoblarce MWS-200. W trakcie badań statutowych wspomagano się oprogramowaniem do badań numerycznych, umożliwiającym przeprowadzenie prób wyoblania. Przedstawiono wyniki prac prowadzonych dla przemysłu, m.in. oświetleniowego, wentylacyjnego, motoryzacyjnego, lotniczego i spożywczego. Pokazano przykładowe wyroby wykonane metodą wyoblania, w tym wyroby wykonane z blachy perforowanej, stali nierdzewnej i aluminium. Ponadto zaprojektowano, wykonano i wdrożono maszynę przeznaczoną do łączenia ze sobą elementów wentylacji. W omawianym okresie Zakład Tłoczenia uczestniczył w realizacji 8 projektów unijnych i krajowych, z czego trzy z nich są nadal realizowane. Zakres prowadzonych prac dotyczył m.in.: walcowania płaskowników o zmiennym przekroju; walcowania pierścieni na gorąco wraz z analizą rozkładu temperatury podczas trwania procesu; gięcia wyciskanych profili aluminiowych o długości do 13 metrów, wykonanych ze stopów serii 5xxx i 6xxx; walcowania na zimno z zastosowaniem układu grzewczo-chłodzącego pomiędzy klatkami linii walcowniczej; modernizacji specjalnej prasy do zgrzewania pasów z włókna szklanego o szerokości do 2,5 m; gięcia profili cienkościennych o zmiennym przekroju z zastosowaniem miejscowego podgrzewania laserem diodowym.
EN
This article presents the scope of works performed at the Press Forming Department of the Łukasiewicz Research Network – Metal Forming Institute in recent years. It includes the results of tests, including statutory works, associated with spinning of axially asymmetrical products on the MWS-200 spinning lathe designed especially for this purpose by the Press Forming Department. Over the course of statutory works, numerical simulation software was used to assist and enable the performance of spinning tests. The results of works performed for industry, including: lighting, ventilation, automotive, aviation and food, are presented. Examples of products made using the spinning method are shown, including products made of perforated sheet, stainless steel and aluminum. Moreover, a machine intended for joining of ventilation elements was designed, made and implemented. During the period under discussion, the Press Forming Department participated in the realization of 8 EU and domestic projects, three of which are still underway. The scope of performed works concerned, among other things: rolling of flat bars with variable cross-section; hot-rolling of rings along with analysis of temperature distribution over the duration of the process; bending of extruded aluminum profiles with length up to 13 meters, made from 5xxx and 6xxx series alloys; cold rolling with the application of a heating and cooling system between cages of the rolling line; modernization of a special press for bonding of glass fiber belts with a width up to 2.5 m; bending of thin-walled profiles of variable cross-section with the application of local heating using a diode laser.
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EN
The paper presents the analysis of the influence of laser assisted machining (LAM) on various parameters of surface roughness of stainless steel. The tests were carried out for cemented carbide inserts with varying cutting parameters. In most cases, a significant reduction in the roughness parameters was observed using LAM.
PL
Przedstawiono analizę wpływu laserowego wspomagania skrawania (LAM) na różne parametry chropowatości powierzchni stali nierdzewnej. Badaniom przy zmiennych parametrach skrawania poddano płytki wykonane z węglika spiekanego. W większości przypadków zauważono wyraźne zmniejszenie wartości parametrów chropowatości po zastosowaniu LAM.
EN
Resistance spot welding (RSW) is a fabrication process that is being used in the automobile and aerospace industry since many years for joining low carbon or “mild” steel. Quality and strength of the welds depend upon the process parameters of RSW. The most effective parameters in this process are: current intensity, welding time, sheet thickness and material, geometry of electrodes, electrode force, and current shunting. This paper presents the experimental investigations for the optimization of tensile shear stress of RSW for stainless steel grade 316L sheets by using Taguchi method. The experiments were conducted using Taguchi’s L27 orthogonal array under varying proces parameters, namely electrode diameter, welding current, and heating time. The experimental data were analyzed using signal-to-noise ratio (S/N ratio) to find the optimal process parameters. Analysis of variance (ANOVA) and F test were used to find the most significant parameters affecting the spot weld quality characteristics. Confirmation tests with optimal process parameters were conducted to validate the test results. From the results, itwas found that it is possible to increase tensile shear stress significantly.
EN
One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process. The technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. Conventional turning machines belong to the basic equipment of ships, because in sea conditions, they enable the execution of a spare part or carrying out the necessary operations in the process of their regeneration. The use of modern cutting tools makes it possible to obtain a surface with low values of surface roughness parameters. The use of new generation cutting inserts on conventional lathes can cause problems for operators. The lack of the ability to ensure proper of treatment condition and setting errors of cutting tools contribute to the damage of the cutting insert or the surface of the workpiece. The article presents the results of influence of different cutting parameters on surface topography during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal TUM 25B x 500 centre lathes. During the turning the following machining parameters were used: cutting speed Vc [m/min], feed f [mm/rev] and depth of cut ap [mm].The turning process was conducted by a cutting tool with CCGT 09T302 UM, CCGT 09T304 UM and CCGT 09T308 UM inserts. Measurement of surface topography was carried out by T8000 profilometer.
EN
One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process. The technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. It is crucial to find a suitable solution which will meet the requirements as well as the work conditions of a given machine part. The article presents the results of influence of change of cutting parameters on surface roughness parameter during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The chemical composition of steel was measured by Solaris-ccd plus optical spectrometer. The cutting process was carried out on a universal CDS 6250 BX-1000 centre lathes. Measurement of surface roughness was carried out by T8000 profilometer. The turning process was conducted by a cutting tool with Wiper insert. During the turning, the following machining parameters were used: cutting speed Vc [m/min], feed f [mm/rev], cutting depth ap [mm] and additionally changed nose radius r [mm], and tool cutting edge angle ϰr [º]. The results of measurements of Ra parameter underwent statistic analysis. The calculations were conducted by Statistica software.
EN
The paper presents results of microscopic tests as well as results of tests concerning mechanical properties of MAG (136) welded joints in duplex steel X2CrNiMoN22-5-3 (1.4462). The research involved metallographic tests of the base material, heat affected zone and weld metal as well as Vickers hardness tests, static tensile tests, bend tests and the identification of a ferrite content obtained using a ferritiscope. The results of observations involving the microstructure of the particular zones of the welded joint as well as the quantitative analysis of phases and the results of the tests concerning the mechanical properties of the joints enabled the formulation of conclusions regarding the microstructure and the mechanical properties of the test joints.
PL
Przedstawiono wyniki badań metalograficznych oraz badań własności mechanicznych złącza doczołowego wykonanego metodą MAG(136) stali dwufazowej ferrytyczno- austenitycznej (duplex) X2CrNiMoN22-5-3 (1.4462). Przeprowadzono badania metalograficzne materiału rodzimego, strefy wpływu ciepła i spoiny oraz pomiary twardości metodą Vickersa, próbę statycznego jednoosiowego rozciągania, próbę zginania bocznego oraz pomiar zawartości fazy magnetycznej za pomocą ferrytoskopu. Na podstawie otrzymanych mikrostruktur z poszczególnych stref złącza, analizy ilościowej występujących faz oraz wyników badań własności mechanicznych wyciągnięto wnioski na temat mikrostruktury badanego złącza oraz jego własności.
EN
This paper discusses issues related to optimising the technological parameters of the process of brazing gold in a vacuum furnace. An investigation of the brazing process was carried out for materials used in constructing components for aircraft engine fuel systems. The vacuum brazed material was AMS 5510 stainless steel (in the form of plates and pipes). AMS 4787 (BAu-4) was used as the brazing filler. In particular, the influence of the method of preparing the surface on solder spreading and the thickness of the diffusion zone were analysed. The best spreading of solder was obtained for nickel plated surfaces. When the sample surface was more rough or scratched, the effect of the spreading of solder was limited and the diffusion process of the solder into the base material became dominant. Moreover, the influence of the brazing temperature on microstructure changes and on interdiffusion of the AMS 5510 stainless steel/BAu-4 solder system was determined. It was observed that an increase in the brazing temperature modifies the morphology of the formed joint by forming a massive and rounded phase. Furthermore, an increase in the brazing temperature enhances the exchange of components.
EN
In this study, ODS ferritic stainless steels were fabricated using a commercial alloy powder, and their microstructures and mechanical properties were studied to develop the advanced structural materials for high temperature service applications. Mechanical alloying and uniaxial hot pressing processes were employed to produce the ODS ferritic stainless steels. It was revealed that oxide particles in the ODS stainless steels were composed of Y-Si-O, Y-Ti-Si-O, and Y-Hf-Si-O complex oxides were observed depending on minor alloying elements, Ti and Hf. The ODS ferritic stainless steel with a Hf addition presented ultra-fine grains with uniform distributions of fine complex oxide particles which located in grains and on the grain boundaries. These favorable microstructures led to superior tensile properties than commercial stainless steel and ODS ferritic steel with Ti addition at elevated temperature.
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Purpose: The paper describes the use of artificial neural networks to research and predict the effect of chemical components and thermal treatment conditions on stainless steel's mechanical characteristics optimized by genetic algorithm. Design/methodology/approach: The quantity of input variables of artificial neural networks has been optimized using genetic algorithms to enhance the prediction quality of artificial neural network and to enhance their efficiency. Then a computational model was trained and evaluated with optimized artificial neural networks. Findings: Optimization, with the exception of tensile strength, has enabled the creation of artificial neural networks, which either showed a better or similar performance from base networks, as well as a decreased amount of input variables As a consequence, noise data is decreased in the computational model built with the use of these networks. Research limitations/implications: Data analysis was required to confirm the relevance of obtaining information used for modelling to use in training procedures for artificial neural networks. Practical implications: Using artificial intelligence enables the multi-faceted growth of stainless steel engineering, even though there is only a relatively small amount of descriptors. Built and optimized computational model building using optimized artificial neural networks enables prediction of mechanical characteristics after normalization of forged ferritic stainless steels. Originality/value: In order to decrease production expenses of products, an introduced model can be obtained in manufacturing industry. It can also simplify the selection of materials if the engineer has to correctly choose chemical elements and appropriate plastics and/or heat processing of stainless steels, having the necessary mechanical characteristics.
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The paper presents the technology of manufacturing layered castings, consisting of grey cast iron (base part) and high-chromium stainless steel (working part/layer). The aim of researches was an attempt of integration of heat treatment of steel X46Cr13 grade with founding of grey cast iron in bimetallic system and determination of the influence of cooling rate of bimetallic system in classical sand mould with bentonite on microstructure and hardness of the working layer. The castings were manufactured using mould cavity preparation method, where steel plate was poured by grey cast iron using different pouring temperature and thickness of base part. Then, the quality of joint between cast iron and steel plate was estimated by using ultrasonic non-destructive testing. The efficiency of heat treatment process was analysed by measurement of hardness and in metallographic examination. Conducted studies showed, that self-hardening’s ability of steel X46Cr13 let obtain technologically usable layered casting characterized by hardness of working surface up to 35 HRC.
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