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1
Content available Defects analysis of seat belt tensioner cast body
EN
The article presents an analysis of the implementation of a selected element of the traveler safety system used in road transport. The results of metallographic tests were presented, and the state of stress introduced to the casting by means of forming the element by means of plastic forming was analyzed. An analysis of the manufacturing process was carried out indicating the risks that may lead to cracks in the material structure. Possible causes of founding defects were pointed out and possible technological solutions were pointed out in order to avoid them.
PL
W artykule przedstawiono analizę wykonania wybranego elementu wyposażenia systemu bezpieczeństwa podróżnych, stosowanego w transporcie samochodowym. Przedstawiono wyniki badań metalograficznych oraz dokonano analizy stanu naprężeń wprowadzanych do odlewu poprzez kształtowanie elementu metodą obróbki plastycznej. Dokonano analizy procesu wytwarzania wskazując na zagrożenia, które mogą prowadzić do powstawania pęknięć w strukturze materiału. Wskazano na możliwe przyczyny powstawania wad odlewniczych oraz wskazano możliwe rozwiązania technologiczne w celu ich uniknięcia.
EN
The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. As an experimental material, the AlSi12 and AlSi7Mg0.3 alloys were used. The influence of process parameters variation (pouring temperature, mold temperature) on mechanical properties and structure will be observed. For the AlSi7Mg0.3 alloy, a pressure of 30 MPa was used and for the AlSi12 alloy 50 MPa. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15 mm, 4 mm, 5 mm, 6.3 mm and 8 mm. The width of each wall was 22 mm and length 100 mm. The mechanical properties (Rm, A5) for individual casting parameters and their individual areas of different thicknesses were evaluated. For the AlSi7Mg0.3 alloy, the percentage increase of the tensile strength was up to 37% and the elongation by 400% (at the 8 mm thickness of the casting). For the AlSi12 alloy, the strength increased from 8 to 20% and the tensile strength increased from 5 to 85%. The minimum thickness of the wall to influence the casting properties by pressure was set to 5 mm (based on the used casting parameters). Due to the effect of the pressure during crystallization, a considerable refinement and uniformity of the casting structure occured, also a reduction in the size of the eutectic silicate-eliminated needles was observed.
EN
Results of a research on influence of chromium, molybdenum and aluminium on structure and selected mechanical properties of Ni-Mn- Cu cast iron in the as-cast and heat-treated conditions are presented. All raw castings showed austenitic matrix with relatively low hardness, making the material machinable. Additions of chromium and molybdenum resulted in higher inclination to hard spots. However, a small addition of aluminium slightly limited this tendency. Heat treatment consisting in soaking the castings at 500 °C for 4 h resulted in partial transformation of austenite to acicular, carbon-supersaturated ferrite, similar to the bainitic ferrite. A degree of this transformation depended not only on the nickel equivalent value (its lower value resulted in higher transformation degree), but also on concentrations of Cr and Mo (transformation degree increased with increasing total concentration of both elements). The castings with the highest hard spots degree showed the highest hardness, while hardness increase, caused by heat treatment, was the largest in the castings with the highest austenite transformation degree. Addition of Cr and Mo resulted in lower thermodynamic stability of austenite, so it appeared a favourable solution. For this reason, the castings containing the highest total amount of Cr and Mo with an addition of 0.4% Al (to reduce hard spots tendency) showed the highest tensile strength.
EN
The article describes the detection of a defect in a cast iron casting. It analyzes the cause of the crack in the Turbine Component casting. In this article, we are focusing on a particular turbine casting that is commonly used in automobiles as one of the components for turbochargers. The turbine is a casting made of ductile cast iron with a visible crack on the naked eye. The formation of cracks in castings is a common but undesirable phenomenon in the foundry practice. It is important to identify the errors, but also to know the cause of defects in castings. The solution is a detailed error analysis. In this paper I used metallographic analysis and magnetic powder method. The crack formation is due to tension in the casting, which results in tensile, shear, or shear forces. The crack formation kinetics is difficult because it is still very low during hardening and shortly after the casting is overloaded. The crack is most often due to core resistance or shrinkage molds that begin after the surface layer is tightened when the strength of the material is negligible to the end of the crystallisation.
EN
The paper shows the results of research aimed to assess the impact of high squeeze pressure on the porosity of AlZn5Mg alloy castings, including its distribution in slab-type castings with dimensions of 25 x 100 x 200 mm. The research was carried out on castings made by two methods: squeeze casting and gravity casting. The pressing was conducted at a pressure of 100 MPa at an initial mould temperature of 200°C. The research identified the middle and outer parts of the casting. Experimental research was preceded by numerical simulation of the casting solidification, then a porosity assessment was carried out using the hydrostatic weighing method, which was supplemented by structural observations. The results of the research showed a two-fold decrease in the porosity in the middle part of the casting which is most exposed to the occurrence of shrinkage voids formed in the final clotting phase. Structural tests revealed the occurrence of dispersed porosity in castings, mainly of shrinkage and / or shrinkage-gas origin. The impact of pressure of 100 MPa during solidification caused fragmentation of the primary structure of castings, which resulted in a higher grain density.
6
Content available remote Morphology of aluminium with nickel addition on sand casting process
EN
Purpose: This research aimed to examine the morphology, elemental changes, and phase in the aluminium cast alloys with variations in nickel addition of 1%, 2% and 3%. Design/methodology/approach: Aluminium 98% was melted in sand casting process. The sand casting process was operated at 7000C and atmospheric pressure. The addition of nickel contain of 92.19% of its element. Specimens consist of 4 pieces Al-Ni with the size of 1 x 1 x 0.5 cm for morphological testing, while for phase identification testing consist of 4 pieces Al-Ni with the size of 1 x 1 x 2 cm. The morphological testing was performed using FEI Inspect S50 Scanning Electron Microscope (SEM) and the phase characterisation was conducted using Nikon ME5 Optical Microscope. Findings: The results showed that the addition of 1% nickel in the aluminium cast product could affect the morphology in granular shape with as similar size, at 2% nickel addition also has granular shape, while at 3% of nickel addition, the morphology of Al-Ni was in elongated shape. Phase identification of Al-Ni cast alloy shows that there were Al matrix with nickel that spread in grain boundary of Al. By increasing the percentage of nickel, it shows that the nickel dominated the grain boundary of Al. These results shows that Al-Ni alloy can be produced at simple route on sand casting process. Research limitations/implications: Sand casting process with 80% silica sand, 10% bentonite, 5% water. Raw material of aluminium contains of 92-99% of purity. Nickel as addition element contain of 90-92% purity. Practical implications: The addition of nickel should be prepared wisely in term of the calculation of alloying treatment because it will effect the mechanical properties of Al alloy itself. This research can be improved by varying the temperature of casting process, variation of nickel percentage, and observation of mechanical properties of Al-Ni alloy. Originality/value: Simple route of making Al-Ni alloy using sand casting method in laboratory and also the observation of nickel addition in aluminium matrix as the result of casting product.
7
EN
Al-4.5Cu alloys are widely used in aerospace industries due to their low weight and high mechanical properties. This group of aluminium alloys is known as 2xx series and exhibits the highest mechanical properties however this alloy is known to suffer from feedability and high tendency for hot tearing. Al-Si alloys (3xx) have improved fluidity and better feedability particularly by several modifications such as Ti, B or Sr. Eutectic temperature is decreased and mechanical properties can be enhanced. Yet, the strength values of this alloy group cannot reach the values of 2xx series. Therefore, in this study, the effect of Ag addition on the fluidity of Al-4.5Cu alloy has been investigated. Standard size spiral mould was used. The casting temperature was selected to be 770oC. Five castings were made and Weibull statistical approach was used to evaluate the results. In addition, coating of the die with BN was also investigated. It was found that Ag addition and BN coating of the die revealed the most reproducible, reliable and high fluidity values.
EN
This work focuses on the influence of temperature distribution in a shell mould during investment casting of thin wall parts on macrostructure, chemical composition of microstructural constituents and γ/γ′ misfit parameter. A reduction of production costs is associated with the optimization of precision casting technology of aircraft engine critical parts, including control of the solidification front in thin-walled castings of nickel superalloys. Appropriate lost-wax casting parameters lead to the creation of coarse grained structure, desired for high-temperature service applications. As a result of non-equilibrium solidification, substantially large chemical inhomogeneities in the dendrite core and interdendritic spaces are formed. Interdendritic spaces are occupied by constituents formed as a consequence of segregation of alloying elements, namely eutectic islands γ/γ′, borides, carbides, and an intermetallic compound of Ni and Zr. Dendrite cores consist of cubic-shaped γ′ precipitates surrounded by Ni-rich γ channels. Low lattice misfit influences cubic morphology of γ′ precipitates, which is favourable for jet engine application because it can guarantee good creep resistance.
PL
Napawanie jest szeroko stosowaną metodą naprawiania powierzchni. Pozwala między innymi na uzupełnienie miejsc, w których uprzednio wystąpiły wżery korozyjne. Techniki napawania wykorzystywane są również do przywracania pierwotnego kształtu zużytych części. W pracy wykonano badania napoin wykonanych elektrodami otulonymi na czołowych powierzchniach cylindrycznych próbek ze staliwa LH14. Proces wykonywano dwoma rodzajami elektrod: Castolin 6601 (przeznaczoną do napawania staliwa) oraz Castolin Xuper NuceloTec 2222 (do łączenia elementów o dużych gabarytach wykonanych ze stali nierdzewnej, staliwa, bądź żeliwa). Niektóre powierzchnie przed wykonaniem procesu celowo zanieczyszczono, bądź napawano nieprawidłową techniką. Miało to na celu wywołanie niezgodności spawalniczych. Próbki poddano następnie badaniom wizualnym oraz penetracyjnym. Po badaniu penetracyjnym wykonano planowanie czoła na głębokość 1 mm. Wynikało to z faktu, iż po naprawach regeneracyjnych następuje najczęściej usunięcie nadmiaru napawanego materiału. Następnie wykonano drugie badanie penetracyjne, które miało na celu wskazanie obecności ewentualnych niezgodności. Wykazano, iż próbki napawane elektrodą przeznaczoną do tego procesu miały o 35% mniej niezgodności, niż wykonane elektrodą do spawania. Potwierdzono również, iż zanieczyszczenie powierzchni znacząco wpływa na powstanie niezgodności. Cześć z nich miała charakter powierzchowny i nie występowała po typowym dla tej metody naprawczej, usuwaniu nadmiaru materiału.
EN
Pad welding is one of the most common method to repair the surfaces. It helps to recover areas where corrosive wear occurred. It is also used as a method to restore the original shape of worn parts. In this work pad welding on the face on cylindrical specimens of LH14 cast steel made by coated electrodes were carried. For process two types of electrodes were used - Castolin 6601 for pad welding of cast steel and Castolin Xuper NuceloTec 2222 for welding large components made of stainless steel, cast steel or cast iron. Some surfaces were contaminated before the process and others were welded by wrong technique to occur imperfections in specimens. Than samples were subjected to visual and penetrant testing. After the penetrant testing, the forehead was 1 mm deep planned. This was due to the fact that after regeneration processes excess material is often removed. The second penetrant testing was then performed to demonstrate the presence of possible defects. It was found that the samples pad welded with the electrodes for pad welding have 35% less imperfections than the samples made by electrodes for welding. It has also been shown that surface contamination significantly affects to increase number of imperfections. Some of them were superficial and did not appear after the typical repair method, removing excess material.
EN
Metal casting process involves processes such as pattern making, moulding and melting etc. Casting defects occur due to combination of various processes even though efforts are taken to control them. The first step in the defect analysis is to identify the major casting defect among the many casting defects. Then the analysis is to be made to find the root cause of the particular defect. Moreover it is especially difficult to identify the root causes of the defect. Therefore, a systematic method is required to identify the root cause of the defect among possible causes, consequently specific remedial measures have to be implemented to control them. This paper presents a systematic procedure to identify the root cause of shrinkage defect in an automobile body casting (SG 500/7) and control it by the application of Pareto chart and Ishikawa diagram. with quantitative Weightage. It was found that the root causes were larger volume section in the cope, insufficient feeding of riser and insufficient poured metal in the riser. The necessary remedial measures were taken and castings were reproduced. The shrinkage defect in the castings was completely eliminated.
EN
Defects affect the properties and behavior of the casting during its service life. Since the defects can occur due to different reasons, they must be correctly identified and categorized, to enable applying the appropriate remedial measures. several different approaches for categorizing casting defects have been proposed in technical literature. They mainly rely on physical description, location, and formation of defects. There is a need for a systematic approach for classifying investment casting defects, considering appropriate attributes such as their size, location, identification stage, inspection method, consistency, appearance of defects. A systematic approach for categorization of investment casting defects considering multiple attributes: detection stage, size, shape, appearance, location, consistency and severity of occurrence. Information about the relevant attributes of major defects encountered in investment casting process has been collected from an industrial foundry. This has been implemented in a cloud-based system to make the system freely and widely accessible.
EN
This paper presents an experimental analysis, which was carried out to evaluate the addition of nitrogen as an element complementing a chemical composition used for such cast parts. It has been demonstrated that nitrogen is very advantageous in the process of austenitizing and quenching, improving the stability and homogeneity of the alloy structure. Plates used as a lining of rotary mills operating in cement plants are castings, which acquire their properties mainly through proper heat treatment. Together with an appropriate microstructure and chemical composition, correct heat treatment allow to improve the wear resistance and significantly reduce the abrasive corrosion. Extensive investigations enabled establishing an optimum nitrogen content in the chemical composition of thick-walled castings used in cement industry. Results of experiments, managed for the steel of ledeburate type containing 0.8–1.2% of carbon, have found that the optimal level of nitrogen is in the amount of 0.07–0.10%. The proposed modification helped to reduce the amount of an expensive chromium, increase the hardness of the material (by about 2 HRC to 4 HRC), and to achieve the uniform microstructure and hardness, which noticeably improved the lifetime of the rotary mills plates.
PL
Największy odlew staliwny wykonany w Polsce to odlew stojaka walcarki quarto, wykonany w roku 1960 w odlewni Zakładów Mechanicznych „Łabędy”, poddany obróbce skrawaniem w Hucie „Zygmunt” w Bytomiu, przeznaczony do pracy na walcowni taśm i blach grubych w Hucie „Batory” w Chorzowie-Batorym. Odlew wykonany został ze staliwa konstrukcyjnego obecnie oznaczonego jako: 230-450W (PN-ISO 3755:1994). Do zalania formy odlewniczej przygotowano 270 t ciekłego metalu, Po odcięciu nadlewów (o łącznej masie 60 t) i obróbce skrawaniem (30 t) odlew waży 180 t. Przybliżone wymiary gabarytowe odlewu (w pozycji zalewania) to: długość – 10100 mm, szerokość – 3920 mm i wysokość – 1600 mm. W Hucie „Batory” (obecnie HW Pietrzak Holding SA Walcownia Blach Batory w Chorzowie) walcarka nadal pracuje. Do wykonania modelu odlewu i modeli nadlewów zużyto około 37 m3 drewna sosnowego. Wykonanie dołu formierskiego trwało 464,3 godziny, natomiast formę stojaka wykonywało 3 formierzy z 3 pomocnikami pracującymi na dwie zmiany przez 32 dni w ciągu 2712 godzin formierskich i pomocniczych. Do wykonania masy formierskiej zużyto 60 t piasku kwarcowego, 50 t szamotu gruboziarnistego, 4 t grafitu i 5 t gliny formierskiej. Na ochładzalniki wewnętrzne zużyto 8 t prętów stalowych. Suszenie formy trwało 3 dni, natomiast stygnięcie odlewu w formie przez 34 dni. Odlew stojaka walcarki quarto wykonano 56 lat temu, a niniejsze opracowanie stanowi hołd należny polskim odlewnikom, utrwalający ich wiedzę, wysiłek i wyobraźnię przy wykonaniu największego odlewu staliwnego w Polsce, będącego w całości dziełem polskich inżynierów i techników różnych specjalności branży metalowej
EN
The largest steel casting ever made in Poland was the stand for the Quarto plate rolling mill made in 1960 at the ZM Łabędy foundry, machined at the Zygmunt Mill in Bytom, and intended for use at the Batory Mill strip and plate rolling mill in Chorzów-Batory. The casting was made from construction steel which would currently be rated as 230-450W (PN-ISO 3755:1994). For the casting, 70 tonnes of molten metal were prepared, and after removal of the flashing (total mass 60 tonnes) and after machining (total mass 30 tonnes), the casting weighed 180 tonnes. The approximate size of the casting (in casting position) was 10100 mm length, 3920 mm width, and 1600 mm height. The mill is still in operation at what was previously Batory, and is now HW Pietrzak Holding SA Plate Mill Batory in Chorzów. Approximately 37 m3 of pine wood was used for the construction of the model of the mould and flashing. Work on the casting pit lasted 464.3 hours, while work on the mould for the stand took 3 moulders and 3 assistants working double shifts 2712 hours. The moulding sand was made of 60 tonnes of quartz sand, 5 tonnes of coarse chamotte, 4 tonnes of graphite, and 5 tonnes of casting clay. For the interior cooling rods, 8 tonnes of steel rods were used. Drying of the mould lasted three days, and the cast was allowed to cool in the mould for 34 days. The casting of the stand took place 56 years ago, and this paper is a well-deserved homage to the Polish foundrymen who created the casting, honouring their knowledge, effort, and ingenuity in making the largest steel casting in Poland, completely created by Polish engineers and technicians from various branches of the metal industry.
EN
Microstructures of superalloys have dramatically changed throughout the years, as modern technology of its casting or forging has become more sophisticated. The first superalloys have polyedric microstructure consisting of gamma solid solution, some fraction of gamma prime and of course grain boundaries. As demands on higher performance of aero jet engine increases, the changes in superalloys micro-structure become more significant. A further step in microstructure evolution was directionally solidified alloys with columnar gamma prime particles. The latest microstructures are mostly monocrystalline, oriented in [001] direction of FCC gamma matrix. All microstructure changes bring necessity of proper preparation and evaluation of microstructure. Except for the already mentioned structures have gamma double prime and various carbides form can be seen. These structural parameters have mainly positive influence on important mechanical properties of superalloys. The paper deals with a microstructural evaluation of both groups of alloys – cast and as well as wrought. Micro-structure evaluation helps to describe mechanism at various loading and failure of progressive superalloys. Such an example where micro-structure evaluation is employed is fractography of failure surfaces after fatigue tests, which are examples of metallography evaluation de-scribed in this paper as a secondary objective.
15
Content available remote Influence of number of fusions on mechanical properties of Ducinox alloy
EN
Purpose: The purpose of the test was to specify influence of re-fusions of the nickelchromium prosthetic alloy Ducinox on its strength properties. Design/methodology/approach: The tests were carried out on the samples cast of the Ducinox alloy molten once, twice and three times. The hardness has been measured using the Vickers method; the tensile strength has been also specified. The samples designed for strength tests were subjected to X-ray control to find possible defects that would eliminate the samples from further tests. The last test was observation of fractures occurred as a result of the strength tests, under the microscope. Findings: Both hardness measurements and strength tests did not show statistically significant differences among individual groups of samples. Practical implications: Based on the results of the tests carried out, it can be found that re-fusion of the alloy Ducinox has no influence on its tensile strength. Thereby, in the dental technology practice, it is possible to add the casting scrap to pure metallic alloy without influence on strength of prosthetic element castings. Originality/value: This is an well-known method of analysis which is applied in many scientific fields. However in modern prosthetics it is new approach.
EN
The purpose of this study was to establish a relationship between the type of wall connection used in the cast grates, which are part of the equipment operating in furnaces for heat treatment and thermal-chemical treatment, and stresses generated in these grates during the process of rapid cooling. The places where the grate walls are connected to each other are usually characterized by the thickness larger than the remaining parts of walls. Temperature variations in those places are responsible for the formation of hot spots, and in the hot spots temperature changes much more slowly. The type of wall connection shapes the temperature gradient in the joint cross-section, and hence also the value of thermal stresses generated during cooling. In this study, five different designs of the grates were compared; the difference in them was the type of the designed wall connection. The following design variants were adopted in the studies: X connections with and without holes, T connections with and without technological recesses, and R (ring) connection. Numerical analysis was performed to examine how the distribution of temperature changes in the initial phases of the cooling process. The obtained results served next as a tool in studies of the stress distribution in individual structures. The analysis were carried out by FEM in Midas NFX 2014 software. Based on the results obtained, the conclusions were drawn about the impact of different types of wall connections on the formation of thermal stresses in cast grates.
EN
Magnesium alloy with 5 wt% Al, 0.35 wt% Mn and 5 wt% rare earth elements (RE) was prepared and gravity cast into a sand mould. Microstructure investigations were conducted. Analyses of the Mg-Al-RE alloy microstructure were carried out by light microscopy, scanning electron microscopy and the XRD technique. In the as-cast condition, the alloy was composed of α-Mg, Al11RE3 and Al10RE2Mn7 intermetallic phases. Additionally, due to non-equilibrium solidification conditions, an Al2RE intermetallic phase was revealed.
EN
In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.
EN
A new Computer-Aided Design approach is introduced for design of steel castings taking into account the feeding ability in sand moulds. This approach uses the geometrical modeling by a CAD-program, in which the modul “Castdesigner” is implemented, which includes the feeding models of steel castings. Furthermore, the feeding ability is guaranteed immediately during the design by an interactive geometry change of the casting cross section, so that a directional feeding of the solidifying casting from the installed risers is assured.
20
Content available remote Heuristic modeling of casting processes under the conditions uncertainty
EN
In the first part of this paper will be described an analysis of control problems and technical lifetime modeling of continuous casting device crystallizers. A full exploitation of continuous casting equipment (CCE) advantages can only be achieved through a control system that minimizes all undesirable effects on the technological process. Some of the undesirable effects influencing the CCE process effectiveness are the failures and service interruptions. This problem was solved by connection of dependability theory and artificial neural networks. The second part of the article refers to a model in linguistic form used to identify the type of defects present in the tested casting. This model, having the form of an attribute table, has been based on the concepts taken from the theory of rough sets and fuzzy logic. A methodology for construction of a heuristic model of linguistic knowledge was presented along with an example of its implementation based on the use of distributed sources of knowledge.
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