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1

Insight into the corrosion in non-ferrous alloy heat exchangers

Lachowicz Marzena M., Lachowicz Maciej B.

Ochrona przed Korozją

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2025

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nr 1

2--11

EN

Selected issues relating to the corrosion of non-ferrous heat exchanger components in their operating environment have been presented. With the increasing demand for such equipment, the number of reported corrosion-related failures is steadily increasing, resulting in rising operating costs. This paper introduces the different types of corrosion and defines selected corrosion problems affecting aluminium heat exchanger components. Macroscopic images are shown and the mechanism of corrosion caused by the presence of organic decomposition products on the surface of copper elements is discussed. In relation to copper, an example of corrosion caused by sulphate ions is also presented. The study also includes an example related to the hydrogenation of a titanium heat exchanger plate. The analyses presented in this paper are related to engineering practice and are relevant to the design of thermal energy exchange devices. The possibility of early detection of existing corrosion hazards will also help to prevent potential mechanical failures in heat exchangers.

PL

W pracy przedstawiono wybrane zagadnienia związane z korozją nieżelaznych elementów wymienników ciepła w ich środowisku eksploatacyjnym. Rosnący popyt na te urządzenia powoduje, że ilość odnotowanych awarii wywołanych korozją stale wzrasta, co wiąże się z rosnącymi kosztami ich eksploatacji. W pracy przedstawiono różne typy korozji, a także zdefiniowano wybrane problemy korozyjne dotyczące aluminiowych elementów wymienników ciepła. Pokazano obrazy makroskopowe oraz omówiono mechanizm korozji spowodowanej obecnością produktów rozkładu substancji organicznych na powierzchni elementów miedzianych. W odniesieniu do miedzi przedstawiono również przykład korozji wywołanej jonami siarczanowymi. W ramach badań przedstawiono także przykład związany z nawodorowaniem tytanowej płyty wymiennika ciepła. Przedstawione w pracy analizy związane są z praktyką inżynierską i stanowią istotne znaczenie dla projektowania urządzeń służących do wymiany energii cieplnej. Możliwość wczesnej detekcji istniejących zagrożeń korozyjnych pozwoli również zapobiegać potencjalnym awariom mechanicznym w wymiennikach ciepła.

2

Electron beam welding of high-strength aluminium alloys

Śliwiński Piotr, Węglowski Marek St., Kubik Kamil, Gotkowski Piotr

Materials Science and Welding Technologies / Technologie Materiałowe i Spawalnicze

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2024

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Vol. 68, No. 2

art. no. 5

EN

Owing to the greater precision of energy density control, the highest possible metallurgical purity of the process and the lack of sensitivity to reflectivity and surface roughness, electron beam welding is a suitable method for joining aluminium alloys. The paper presents results concerning the welding of aluminium alloy grades 6060 and 6061 as well as experimental alloys having higher copper contents. The tests discussed in the paper led to the obtainment of joints characterised by a high strength of up to 289.7 MPa and the lack of unacceptable imperfections.

PL

Spawanie wiązką elektronów, ze względu na większą precyzję kontroli gęstości energii, najwyższą możliwą czystość metalurgiczną procesu oraz brak wrażliwości na współczynnik odbicia światła i chropowatość powierzchni, jest odpowiednią metodą łączenia stopów aluminium. W niniejszym artykule przedstawiono wyniki spawania stopów aluminium w gatunku: 6060, 6061, a także eksperymentalnych stopów o podwyższonej zawartości miedzi. W ramach badań uzyskano złącza charakteryzujące się wysoką wytrzymałością, nawet do 289,7 MPa, a także brakiem niedopuszczalnych niezgodności.

3

The Role of Molybdenum in the Formation of the Microstructure and Properties of Al-Cu Alloys

Stąpór Sylwia, Górny M., Gondek Ł., Gracz B., Kawalec M.

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 4

39--48

EN

The subject of the presented research is the influence of molybdenum on selected properties of alloys that are based on the Al-Cu system. It could be observed that the introduction of molybdenum to the multi-component alloy at levels of up to 0.5 wt.% showed increases in the degrees of undercooling ΔT along with the increasing contents of the introduced element. The addition of molybdenum contributed to the reduction of the size of the primary grains of the α(Al) phase. Molybdenum improved the strength of the alloy while achieving elongation at a significant level. This is an element that occurs in the alloy – both in the iron-manganese phases and in the segregates inside the grains. Most of the iron-manganese phases occurred in a more spheroidal form. Additionally, tests were carried out on higher molybdenum content in the alloy. The addition of the tested chemical element at a level of 1 wt.% caused the precipitation of the phases that contained molybdenum, which did not dissolve after heat treatment.

4

The Influence of Selected High – Pressure Die Casting Parameters on the Porosity of EN AB-46000 Alloy Castings

Piątkowski Jarosław, Roskosz Stanisław, Stach Sebastian

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 5

361--371

EN

The EN AB-46000 alloy castings are widely used in automotive industry due to their relative good strength combined with a low density and an excellent conductivity. Porosity of EN AB-46000 alloys is one of the most important defects, responsible for the low strength and poor plastic properties of castings as well as their tightness. Quantitative porosity measurement were performed using quantitative metallography and image analysis methods using ImageJ. The study shows that such parameters of high-pressure die casting are the piston speed in the second casting phase and the final pressure increase in the pressing phase. It has been shown that the appropriate selection of these parameters can significantly reduce the porosity of castings made of alloy EN AB-46000.

5

Measurement Methods for Flux Residue Quantity after Controlled Atmosphere Brazing of Aluminum Coolers

Nadolny Sławomir, Hamrol Adam, Rogalewicz Michał, Piasecki Adam

Management and Production Engineering Review

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2023

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Vol. 14, No. 3

156--163

EN

The Controlled Atmosphere Brazing (CAB) process together with NOCOLOKr flux is associated with the occurrence of potassium fluoroaluminate residue inside the cooler. Excess of this flux residue is known to cause gelation of the coolant, which deteriorates the efficiency of the cooler. The flux residue amount is most often measured via Atomic Absorption Spectroscopy (AAS), in accordance with DIN ISO 9964-3. This is a time-consuming measurement that requires the use of specialized equipment and costly solvents. The following article presents two innovative methods for flux residue measurement after CAB process. They include Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) and Reflected Light Microscopy (RLM) with Differential Interference Contrast (DIC) module. The accuracy of these methods has been compared to the reference AAS method to evaluate their potential as alternative, less expensive, and quicker measurement methods for determining the quantity of flux residue.

6

Effect of Inoculation on the Mechanical Properties of AZ91

Rapiejko Cezary, Mikusek D., Kubiak Krzysztof, Pacyniak Tadeusz

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

15--20

EN

The effect of Ca element on the microstructure evolution of the AZ91 magnesium alloy was investigated in this research. The magnesium-aluminium alloy AZ91 was inoculated with the Emgesal® Flux 5 to refine its microstructure and also improve its microstructure. Six different concentrations of the Emgesal® Flux 5 content were tested, ranging from 0.1 to 0.6% wt., and compared to the baseline of the AZ91 alloy without inoculation. Melted metal was poured into a preheated metallic mould. Samples to test were achieved after turning treatment. Formed microstructure was assessed using an optical microscope. The microstructure was refined for every tested samples. Mechanical properties such as tensile strength, elongation, Brinell hardness, Vickers microhardness, abrasion resistance and adhesive resistance were tested on the inoculated samples and compared to the non-inoculated AZ91. Introducing an Emgesal®Flux 5 inoculant caused a change in the tensile strength, elongation, Brinell hardness, Vickers microhardness, abrasive wear resistance as well as adhesive wear resistance in each examined concentration.

7

Application possibilities of scanning acoustic microscopy in the assessment of explosive welding

Korzeniowski Marcin, Białobrzeska Beata, Lewandowska Anna

Materials Science Poland

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2022

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Vol. 40, No. 3

93--111

EN

The last two decades have brought stable and impressive development accompanied by the industry acceptance of the use of high energy techniques based on energy obtained from explosive detonation energy. Such manufacturing processes are not only commercially viable, but also allow complex product shapes and unique combinations of metal sheets in terms of materials to be obtained; they enable the creation of composites which cannot be obtained by other conventional methods. Plated sheets are composed of a base material and a thinner plating material layer. An essential aspect in the validation of explosive welding is the quality control of joints made using this technology. The basic control methods are destructive tests – mainly metallographic, which reveal the microstructure at the connection boundary. Non-destructive tests, used in industrial practice, are classical, normalised ultrasonic tests of welding joints, conducted in accordance with ISO 17640:2017 and ISO 11666:2018 standards. Due to the relatively low thickness of the explosion-tested layers (2 mm and 3 mm single layers), which is the object of this study, assessing them using widely available ultrasonic techniques is limited. According to current scientific studies, the application of the scanning acoustic microscopy (SAM) is a prospective non-destructive method allowing for the qualitative and quantitative assessment of the continuity of the metallic connection on the contact surface of two materials. This paper presents the results of research on the quality of clads, welded explosively using a non-destructive research technique, namely SAM, verified with metallographic tests.

8

Preparation of composite steel with using of hot rolling

Kawulok Rostislav, Pasečný Daniel, Kawulok Petr, Rusz Stanislav, Opěla Petr, Schindler Ivo

Journal of Metallic Materials

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2022

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Vol. 74, no. 1

21--27

EN

The paper deals with the unconventional issue of composite steel preparation by hot rolling. Various production possibilities of multilayer composite from austenitic stainless steel AISI 304 and tool high carbon steel AISI D2 were investigated. Samples with 5, 15 and 45 layers were prepared. Optical microstructural analysis were subsequently performed on these samples with the focus on the details of joint and evaluation of the thicknesses of individual layers. In addition, hardness measurements were performed on the prepared samples, including its comparison with the individual steels used. It was confirmed that the hardness increased with increasing number of layers, however in this case, the difference between 15 and 45 layers was only 8 HBW. In addition it was found that the hardness of the prepared 45-layer packet without quenching was higher than that of the base (used) steels.

PL

Niniejszy artykuł poświęcono niekonwencjonalnemu zagadnieniu przygotowania kompozytu stalowego metodą walcowania na gorąco. Zbadano różne możliwości i metody wytwarzania wielowarstwowego kompozytu stalowego z austenitycznej stali nierdzewnej AISI 304 i wysokowęglowej stali narzędziowej AISI D2. W pracy opisano technologię przygotowania pakietów z tych stali złożonych z 5, 15 i 45 warstw. Następnie przeprowadzono na tych próbkach optyczne analizy mikrostrukturalne, skupiając się na szczegółach łączenia i ocenie grubości poszczególnych warstw. Ponadto na przygotowanych próbkach wykonano pomiary twardości, a wyniki porównano z poszczególnymi zastosowanymi stalami. Potwierdzono, że twardość wzrastała wraz ze wzrostem liczby warstw, jednak w przypadku różnicy między 15 a 45 warstwami różnica twardości to zaledwie 8 HBW. Ponadto stwierdzono, że twardość przygotowanego 45-warstwowego pakietu bez hartowania była wyższa niż (użytych) stali podstawowych.

9

Mechanical and Microstructural Characterization of Aluminium Alloy, EN AC-Al Si12CuNiMg

Sirata Gotfila G., Wacławiak K., Dyzia Maciej

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

34--40

EN

the manufacture of mechanical structures where low weight is critical. However, when these alloys are subjected to elevated temperatures, their mechanical properties deteriorate significantly. The aim of this study is to investigate the effect of temperature on the mechanical properties of aluminium alloy, EN AC-Al Si12CuNiMg. For this purpose, an experimental investigation was performed at ambient and elevated temperatures on aluminium alloy samples prepared by casting. Tensile and hardness tests were carried out to characterize the mechanical properties of this material. Additionally, an optical microscope was used to examine the microstructures of this alloy. Finally, a scanning electron microscope was used to analyze the fracture modes of this material. The results show that the mechanical properties such as tensile strength, yield strength, and Young's modulus of this alloy dramatically decrease when the temperature exceeds 250oC. The microstructural investigation reveals several factors that are detrimental to the mechanical properties of this alloy. This includes coarse-grained structures, micro-pores, and several intermetallic compounds. Furthermore, fractography reveals a minor cleavage-like pattern and micro-cracks on the fracture surface of all failed samples under various temperatures, indicating semi-brittle fracture mode.

10

Study of the Properties of the AlSi9Cu3 Alloy Depending on the Ratio of Returnable Material in the Batch

Matejka M., Bolibruchová D., Chalupová M.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

15--23

EN

Recycling of aluminium returnable material through its reuse is now an essential component of the production of aluminium alloy castings. The main goal is to find a suitable ratio of the primary alloy and the returnable material in the batch, thus determining the right compromise between the price and the quality of the casting. Experimental alloys were evaluated by thermal analysis, combination of structural analytical techniques and selected mechanical properties. The alloys were also subjected to tearing susceptibility testing. The increase in the returnable material amount resulted in changes in the alloy properties at the first increase in volume to 20%. After exceeding the balanced ratio (50:50), there was considerable degradation of the microstructure, failure to achieve the minimum values of some mechanical properties required by the standard, and the alloy showed increased susceptibility to tearing.

11

Influence of Tungsten on the Structure and Properties of Ductile Iron Containing 0.8% Cu

Myszka Dawid, Kasińska J., Penkul A.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 4

121--126

EN

The possibilities of producing ductile cast iron with the addition of 1÷3% of tungsten are presented. Tungsten from waste chips from mechanical processing was introduced into the liquid cast iron in the form of specially prepared cartridges. Correct dissolution of tungsten in the metal bath was found, and there were no casting defects in the alloy. The form of carbide precipitates in the microstructure of cast iron was determined and the influence of increasing tungsten content on the reduction of the number of graphite precipitates in the structure was determined. Impact tests show that this property degrades with increasing tungsten content as opposed to hardness which increases. It was found that the addition of tungsten from machining waste is a potential source of enrichment of cast iron with this element.

12

Effect of Gadolinium on the Microstructure of Magnesium Alloy AZ91

Rapiejko Cezary, Mikusek D., Just P., Pacyniak T.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

31--36

EN

The paper presents the results of research related to the possibility of inoculation of the AZ91 magnesium alloy casted into ceramic moulds by gadolinium. Effects of gadolinium content (0.1–0.6 wt%) on microstructure of the AZ91 alloy under as-cast state were investigated. The influence of the inoculator on the formation of the microstructure investigated by means of the thermal and derivative analysis by analysing the thermal effects arising during the alloy crystallization resulting from the phases formed. The degree of fragmentation of the microstructure of the tested alloys was assessed by means of the light microscopy studies and an image analysis with statistical analysis was performed. Conducted analyses have aimed at examining on the effect of inoculation of the gadolinium on the differences between the grain diameters and average size of each type of grain by way of measuring their perimeters of all phases, preliminary αMg and eutectics αMg+γ(Mg17Al12) in the prepared examined material.

13

Determination of Phase Transformation Temperatures by Dilatometric Test of S960MC Steel

Málek M., Mičian M., Moravec J.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

57--64

EN

The phenomenon of “soft zone” is occurring in the heat affected zone (HAZ) of high strength low alloy (HSLA) steels. Therefore, the process of weld metal solidification and phase transformation in HAZ is essential to understand the behaviour of the material, especially in the case where welded joints are debilitating part of the construction. The simulation program SYSWELD is powerful tool to predict solidification and phase transformation of welding joint, what correspond to the mechanical properties of the joints. To achieve relevant results of the simulation, it is necessary to use right mathematic-material model of the investigated material. Dilatometric test is the important methods to gather necessary input values for material database. In this paper is investigated physical and metallurgical properties of S960MC steel. The dilatometric curves were carried out on the laboratory machine dilatometer DIL 805L. In addition to determination of the phase transformation temperatures at eight levels of the cooling rate, the microstructure and hardness of the material are further analysed. The hardness of the samples reflects the achieved microstructure. Depending on the cooling rate, several austenitic transformation products were observed such as pearlite, bainite, martensite and many different ferritic microstructures. The differences between the transformation temperature results using the first derivation method and the three tangent method are up to 2%. The limit cooling rate was set at value 30°C/s. The microstructure consists only of bainite and marten site and the hardness reaches a value of 348HV and higher.

14

Comparison of Microstructure and Mechanical Properties of Cast Steel Carried out on Cast-on Samples and Samples Cast Separately

Kalandyk B. E., Zapała R. E.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

81--88

EN

The results of microstructure examinations and UTS, YS, El, RA carried out on low-carbon cast steel containing 0.15% C. The tests were carried out on specimens cut out from samples cast on a large-size casting and from samples cast in separate foundry moulds. It has been shown that significant differences in grain size observed in the material of the separately cast samples and cast-on samples occur only in the as-cast. In the as-cast state, in materials from different tests, both pearlite percent content in the structure and mean true interlamellar spacing remain unchanged. On the other hand, these parameters undergo significant changes in the materials after heat treatment. The mechanical properties (after normalization) of the cast-on sample of the tested cast steel were slightly inferior to the values obtained for the sample cast in a separate foundry mould. The microscopic examinations of the fracture micro-relief carried out by SEM showed the presence of numerous, small non-metallic inclusions, composed mainly of oxide-sulphides containing Mn, S, Al, Ca and O, occurring individually and in clusters.

15

Analysis of Fracture Mechanism of Cast Steel for Different States of Stress

Lachowski J., Borowiecka-Jamrozek J.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

29--34

EN

In this paper a plastic deformation and a damage evolution in low-carbon cast steel containing non-metallic inclusions are analysed experimentally and numerically. Two microstructures of the cast steel have been obtained after appropriate heat treatment. Tensile tests of smooth specimens and axisymmetric notched specimens have been performed. The notched specimens have the notch radii: 1 mm, 3 mm and 7 mm. Fractography of the specimens was carried out to observe fracture mechanisms. The mechanism depended on the stress state in the notched specimens. The fractography showed the existence of two fracture mechanisms: ductile failure and by shear. The process of the voids growth formed on the non-metallic inclusions was the process which included in the explanation of the damage mechanism. Modelling of deformation of the specimens has been used with the model suggested by Gurson, Tvergaard and Needleman. The model is implemented in the Abaqus finite element program. The computer simulation was performed using ABAQUS system. The computed output was compared with the experimental results obtained for specimens of the same shape.

16

A Process of As-Cast Ferritic Gray Cast Iron Production

Hossain Md Sojib

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

5--10

EN

Though normal air cooling and green sand mold-casted gray iron convey an essentially pearlitic matrix, ferritic gray iron is used in some electro-mechanical applications to have better magnetic properties, ductility, and low hardness. Conventionally, to produce ferritic gray iron, foundryman initially produces pearlitic gray iron, then it is carried through a long annealing cycle process for ferritic transformation. This experiment is conducted to eliminate the long annealing cycle from the conventional process. A process is developed to produce as-cast ferritic gray cast iron by air cooling in the green sand mold. In this experiment, Si content is kept high, but Mn content is kept low based on sulfur content; a unique thermodynamic process is established for decreasing the Mn content from the melt. After a successful preconditioning and optimum foundry return charging, the melt is specially inoculated, and metal is poured into the green sand mold. An extra feeder is added for slowing down the cooling rate where casting thickness is around 15mm. Finally, hardness and metallographic images are observed for final confirmation of the ferritic matrix.

17

Joining the High-Strength Steel Sheets Used in Car Body Production

Kaščák Ľuboš, Cmorej Denis, Spišák Emil, Slota Ján

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no. 1

184--196

EN

Nowadays, there are several important reasons for using high-strength sheets in the manufacturing of car bodies. Car manufacturers choose the steel with good formability, fatigue resistance and ability to absorb impact energy. Microalloyed steels and dual-phase steels are the materials which fulfil the above-mentioned criteria. The application of high-strength sheets has led to the development of new materials joining techniques. Mechanical joining, such as clinching, is the innovative technique to join these progressive materials. Materials of different thicknesses can be joined by clinching. The paper focuses on the comparison of the properties of the joints made by clinching and resistance spot welding. The application of resistance spot welding is still the most used joining method in car body production. These properties were investigated by tensile test and metallographic observation. The HCT600X+ZF, HCT600X+Z and HX420LAD+Z steel sheets were used for the experiments. The results of tensile test show that the values of load-bearing capacity of clinched joints reached from 3900 N to 5900 N and the resistance spot welded joints reached the values of load-bearing capacity from 12000 N to 19500 N. In comparison to the resistance spot welded joints, the clinched joints reached from 32 to 48% of load-bearing capacity.

18

Microstructural aspects of repairing unalloyed cast steel with around 0.3% carbon content using welding technology

Lachowicz Maciej B., Lachowicz Marzena M.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2020

|

nr 61 (133)

130--135

EN

In this work, the results of tests on castings made from unalloyed cast steel, which was repaired using surface padding, have been presented. The purpose of the work was to present the impact of the application of welding technology on the microstructure of cast steels and the dangers related to it. The appearance of a very adverse microstructure was found in the area where the padding occurred. In the light of the presented research, it seems that it is necessary to apply normalizing annealing after the padding of a cast, which will result in a more uniform and fine microstructure of the material being obtained. As a consequence, this will prevent possible operating damage from occurring in the finished products.

19

Tribological Wear of as Cast Zn-4Al Alloy Cooled at Various Rates from the Eutectoid Transformation Temperature

Lachowicz M. M., Leśniewski T., Lachowicz M. B., Jasionowski R.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 4

108--114

EN

The paper presents the results from a study on the impact of the cooling rate in the eutectoid transition on the abrasive wear of the as cast Zn-4Al alloy. The microstructure of the researched material consists of dendrites of the η solid solution and an (α+η) eutectic structure. During the eutectoid transformation at 275oC the distribution in the eutectic structure was transformed and fined. Heat treatment was carried out for this alloy, during which three cooling mediums were used, i.e. water, air and an furnace. For the research material obtained in this way, metallographic examinations were performed using the methods of light and scanning electron microscopy, as well as hardness measurements. It was found that faster cooling rate promoted the fragmentation of structural components, which translates into higher hardness of the material. This also had effects in the tribological wear of the tested alloy. As part of the tests, an abrasive wear test was carried out on a standard T-07 tester.

20

Preconditiong and Inoculation of Low Sulphur Grey Iron

Hossain Md Sojib S., Bazlur B. Rashid A. K. M.

Archives of Foundry Engineering

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2020

|

Vol. 20, iss. 1

61--66

EN

For quality grey cast iron production, the challenging issues are to avoid cementite structure and obtain the desired graphite morphology with proper matrix as well as hardness. The objective of the present research is to find out the right combination of preconditioner and inoculant that may help to overcome the challenges. In this work, sulphur content is kept low (0.01%). Two preconditioners namely metallurgical SiC and zirconium bearing FeSi with two types of inoculant are individually used to make four combinations of sample and for each case metal is poured into the green sand mould. Finally Brinell hardness and graphite morphology is observed in the thickest and thinnest portions of the castings. Metallurgical SiC with barium bearing inoculant gives better graphite morphology and hardness than strontium bearing inoculant, on the other hand zirconium bearing FeSi gives more satisfying result than SiC with every type of inoculant. Among all of the combinations Zr bearing preconditioner with Ba bearing inoculant gives good graphite morphology with best mechanical properties in both thickest and thinnest portions of the casting.