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1

Evaluation of Permeability Models for Foundry Molds and Cores in Sand Casting Processes

Sundaram Dinesh, Matsushita Taishi, Belov I., Diószegi Attila

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

94--106

EN

Predicting the permeability of different regions of foundry cores and molds with complex geometries will help control the regional out gassing, enabling better defect prediction in castings. In this work, foundry cores prepared with different bulk properties were characterized using X-ray microtomography, and the obtained images were analyzed to study all relevant grain and pore parameters, including but not limited to the specific surface area, specific internal volume, and tortuosity. The obtained microstructural parameters were incorporated into prevalent models used to predict the fluid flow through porous media, and their accuracy is compared with respect to experimentally measured permeability. The original Kozeny model was identified as the most suitable model to predict the permeability of sand molds. Although the model predicts permeability well, the input parameters are laborious to measure. Hence, a methodology for replacing the pore diameter and tortuosity with simple process parameters is proposed. This modified version of the original Kozeny model helps predict permeability of foundry molds and cores at different regions resulting in better defect prediction and eventual scrap reduction.

2

Regularities of Crystallization Heat Release During Solidification of Alloyed Cast Irons

Aftandiliants Y., Gnyloskurenko S., Meniailo H., Khrychikov V., Lomakin V.

Archives of Foundry Engineering

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2023

|

Vol. 23, iss. 1

110--117

EN

The chemical composition of alloys plays an important role at their crystallization and influences the solid phase formation, and thus, microstructure and properties. The present paper studies the release of the heat of crystallization of alloyed wear-resistant cast irons in order to determine the quantitative patterns of the chemical composition influence to the kinetics of crystallization. The differential thermal analysis was applied to get the data of heat release, its rate at cast iron temperature decrease. The normalized dependence of the amount of crystallization heat over time was obtained. The main temperature parameters were analyzed and four stages at irons crystallization were established and characterized with their duration and released heat. The multiple correlation analysis allowed considering a numerous physical and chemical factors and distinguishing their role at crystallization of irons. As a result, the quantitative regularities are determined of influencing the content of alloying elements, impurities and carbides on a heat and time of crystallization at the different stages of solidification, which are of great importance in developing alloyed irons with required quality and properties.

3

Numerical Modelling for the Effect of Metal-mould Air Gaps on Shell Thickness in Horizontal Continuous Casting of Cast Iron

Chawla Ashish, Tiedje N. S., Spangenbe Jon

Archives of Foundry Engineering

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2023

|

Vol. 23, iss. 1

53--60

EN

This paper presents a numerical model for the horizontal continuous casting of cast iron (HCCCI). A computational three-dimensional (3D) steady-state, coupled with fluid flow and heat transfer simulation model was developed and validated against experimental results to study the shell thickness and solidification of ductile cast iron. The study introduces the influence of an air gap at the melt-mould interface, which has long been known to have a detrimental effect on the efficiency of the process. The effect of the length and thickness of the melt-mould air gaps (also referred to as top air gaps) on solidification and remelting of the solid strand is studied. Parametric studies on top air gaps suggested a substantial effect on the solid and eutectic area at the top-outlet end of the die when the length of air gas was varied. This study serves to create a foundational and working model with the overall objective of process optimisation and analyzing the effect of operating process input parameters on the shell thickness of the strand.

4

Studies of mechanical and technological parameters and evaluation of the role of lustrous carbon carriers in green moulding sands with hybrid bentonite

Kamińska Jadwiga, Stachowicz Mateusz, Puzio Sabina, Angrecki Michał

Archives of Civil and Mechanical Engineering

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2023

|

Vol. 23, no. 1

art. no. e11, 2023

EN

Green moulding sands containing special carbonaceous additives, which are the source of lustrous carbon (LC), are discussed in this paper. Five potential lustrous carbon carriers, i.e., two types of hard coal dust (No.1 and No.2), amorphous graphite (No.3) and two hydrocarbon resins (No.4 and No.5), were selected for tests as carbonaceous additives to conventional moulding sands. To better emphasize the differences in the additives used, reference green moulding sand (GMS1) was prepared and subjected to a wide range of basic tests focussed on technological parameters, such as permeability (Pw), friability (Fw), Dietert mouldability test (PD) and compactability (Z) and mechanical parameters, such as compressive strength (Rcw), tensile strength (Rmw), strength in the transformation zone (Rkw). The proposed comprehensive spectrum of tests was repeated on sands with five carbonaceous additives. The most important for the use of additives as carbon carriers was to interrelate the content of lustrous carbon (LC), loss on ignition (LOI) and the obtained results of mechanical and technological tests carried out on conventional moulding sands with the surface quality of iron castings. For this purpose, a series of iron castings was made in the prepared moulding sands and used for the assessment of surface quality based on a number of roughness parameters (Ra, Rz, Rp, Rq, Rv, Rlr, RSm). As a result of the studies it was found that the carbonaceous additives proposed for use help to obtain high-quality surfaces in iron castings.

5

Composite Material with Cast Iron Matrix Designed for Brake Systems of Technical Means of Transport

Posmyk Andrzej, Myalski Jerzy

Tribologia

|

2022

|

nr 3

79--86

EN

The paper presents the basics of manufacturing and the tribological properties of the developed cast iron-ceramic composite designed for brake discs or drums. The matrix of the composite consists of GJL-150 grey cast iron used for the production of brake discs. The reinforcing phase is a SiC foam with an activated surface. The use of ceramic foam simplifies the production process because it does not require expensive mixing of the matrix and the reinforcing phase to ensure the homogeneity of the composite. An addition of 10% SiC (λSiC= 100–350 Wm-1K-1) improves the thermal conductivity of cast iron (λCI = 50–60 Wm-1K-1). The presence of foam elements homogenously distributed throughout the whole matrix volume reduces the wear of both the composite and the counter-sample. The results of comparative studies of contacts between the cast iron and the composite brake disc showed almost a threefold lower wear of the pad and disc and about a 10°C lower temperature in the pad near the friction zone under the pressure of 1 MPa and at a sliding velocity of 0.5 m/s. The significantly lower wear of the friction elements of the brake system will contribute to a reduction in environmental pollution by wear debris, which is required by European Union directives.

PL

W artykule opisano podstawy wytwarzania i właściwości tribologiczne opracowanego kompozytu żeliwno-ceramicznego przeznaczonego na tarcze lub bębny hamulcowe. Osnowę kompozytu stanowi stosowane do wytwarzania tarcz hamulcowych żeliwo szare GJL-150, a umocnieniem jest pianka z SiC z aktywowaną powierzchnią. Użycie pianki ceramicznej upraszcza proces wytwarzania, ponieważ nie wymaga kosztownego mieszania osnowy i fazy zbrojącej dla zapewnienia homogeniczności kompozytu. Dodanie 10% pianki SiC (λSiC= 100–350 Wm-1K-1) poprawia przewodność cieplną żeliwa (λCI = 50–60 Wm-1K-1). Obecność równomiernie rozłożonych w całej objętości osnowy elementów pianki zmniejsza zużycie zarówno kompozytu, jak i współpracującego z nim materiału ciernego. Wyniki badań porównawczych skojarzeń z tarczą żeliwną i kompozytową wykazały mniejsze prawie trzykrotnie zużycie klocka i tarczy oraz niższą o 10°C temperaturę w klocku w pobliżu strefy tarcia przy nacisku 1 MPa i prędkości 0,5 m/s. Znacząco zmniejszone zużycie elementów ciernych układu hamulcowego przyczyni się do zmniejszenia zapylenia środowiska produktami zużycia, co jest wymagane w dyrektywach Unii Europejskiej.

6

Effect of internal polyurethane coatings of cast iron pipes on the quality of transported potable water

Zielina Michał, Młyńska Anna

Environment Protection Engineering

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2022

|

Vol. 48, nr 3

25--38

EN

The paper presents the results of laboratory tests to determine the effect of an internal polyurethane coating in ductile iron pipes on the quality of disinfected and non-disinfected drinking water. A decrease in the pH of water in contact with the polyurethane coating was found, which was slightly higher in the non-disinfected water than in the disinfected water. The coefficient of variation (CV) of the pH values for the chlorinated water samples was 5.02% and for the non-chlorinated water was 7.15%. The experiments also showed a rather large effect of polyurethane liner on the increase of TOC concentration in water. The presence of disinfectant further slightly increased the amount of organic compounds released. The CV values normalized to one day for TOC were as high as 193.32% and even 199.39% for disinfected water. A significant effect of polyurethane coating was observed on the color change and odor of water. On the other hand, there was no effect of polyurethane coating on alkalinity and chlorine consumption in water. The CV values normalized to one day in both cases were very small at 0.97% and 0.53%, respectively.

7

Wettability of the System of Cast Iron and Magnesia Ceramics with Graphite

Hosadyna-Kondracka Małgorzata, Nowak Rafał, Turalska Patrycja, Bruzda Grzegorz, Boroń Łukasz, Wawrylak Marek

Archives of Foundry Engineering

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2022

|

Vol. 22, iss. 3

25--33

EN

In this paper examinations of high-temperature wetting tests of 3 systems of liquid alloy – cast iron in contact with ceramic materials: magnesia ceramics in combination with natural graphite were presented. After wettability testing, the microscopic observations of the morphology of the sample surface and the cross-section microstructure with the chemical composition in micro-areas were examined. One of the objective of this work was also to verify whether the graphite content would affect the wettability of the magnesia ceramics. The study of high-temperature wetting kinetics of the liquid alloy in contact with the ceramic material, by the "sessile drop" method with capillary purification (CP) procedure was conducted. Under the test conditions, at a temperature of 1450°C and time 15 minutes, all 3 experimental systems showed a non-wetting behaviour. The average contact angle for the system with cast iron drop on magnesia ceramics was 140°, on magnesia ceramics with 10 parts per weight of graphite was 137° and on magnesia ceramics with 30 parts per weight of graphite - 139°. Microscopic observations revealed that in the case of the sample consisting of the cast iron drop on the substrate with magnesia ceramics, the formation of fine separations was not observed, unlike the systems with the substrate with magnesia ceramics and the addition of natural graphite. Numerous, fine droplets accumulate on the graphite flakes and consist mainly of Si as well as Fe and O. On the other hand, the rough MgO grains have a gray, matt surface, without fine separations. The conducted observations indicate the mechanical nature of the bonding - liquid metal penetrates into the pores of the rough ceramics of the substrate. However, in the case of systems of cast iron drop with magnesia ceramics and addition of graphite, probably the adhesive connection and the physical attraction of elements derived from cast iron drop with the flake graphite appeared as well.

8

Investigation of the Effect of Solidification Time and Addition Amount of Inoculation on Microstructure and Hardness in Lamellar Graphite Cast Iron

Çolak Murat, Uslu Emin, Teke Çağatay, Şafak F., Erol Ő., Erol Y., Çoban Y., Yavuz M.

Archives of Foundry Engineering

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2022

|

Vol. 22, iss. 4

24--33

EN

Material suppliers typically recommend different additive amounts and applications for foundry practices. Therefore, even in the production of the same standard materials, different results may be obtained from various production processes on different foundry floors. In this study, the liquid metal prepared with the addition of different proportions of a FeSi-based inoculation, which is most commonly used in foundries in the production of a cast iron material with EN-GJL-250 lamellar graphite cast iron, was cast into sand molds prepared with a model designed to provide different solidification times. In this way, the optimization of the inoculation amounts on the casting structure for different solidification times was investigated. In addition, hardness values were determined depending on solidification time in varying amounts of inoculation additions. SolidCast casting simulation software was used to determine the casting model geometry and solidification time. In the scope of the study, sand casting, modeling, microstructure analysis, image analysis, microstructure analysis, and hardness tests techniques were used. When the results are examined, the required amount of inoculation for the optimal structure is optimized for the application procedure depending on the casting module and the solidification time.

9

Żeliwna klatka schodowa w XIX-wiecznym budynku więzienia przy ulicy Piekary w Toruniu

Lewandowski Łukasz, Kucharzewska Joanna, Pabich Marek

Wiadomości Konserwatorskie

|

2021

|

Nr 67

115--128

PL

W 1859 w Toruniu powstał projekt zespołu budynków sądu i więzienia, dla którego przewidziano narożną działkę u zbiegu ulic Piekary i Fosa Staromiejska. W pierwszej kolejności zrealizowano sąd, później budynek więzienia na planie koła, przypominający istniejącą w tym miejscu basteję zwaną Kocim Ogonem. Projekt funkcjonalno-przestrzenny więzienia zakładał rozmieszczenie cel po obwodzie budynku oraz umieszczenie wewnętrznej klatki schodowej. Architekt planował połączenie tradycyjnej konstrukcji murowanej z nowoczesną technologią, polegającą na użyciu żeliwnej klatki schodowej i żeliwnych wsporników w celu podtrzymania wewnętrznych podestów. Artykuł przedstawia tę nowatorską konstrukcję, stanowiącą pierwszy w Toruniu przykład zastosowania na taką skalę żelaza lanego w budynku municypalnym. Schody wykonano z prefabrykatów, których sposoby montażu i oprawy dekoracyjnej były wówczas novum. Temat stanowi ważny problem badawczy, zwłaszcza w kontekście stanu zachowania żeliwnych klatek schodowych i ginącego dziedzictwa techniki, a także wyzwań konserwatorskich.

EN

In 1859, a design of a complex that consisted of a court and prison building was drafted in Toruń, for which a corner plot at the intersection of Piekary and Fosa Staromiejska streets was assigned. The court building was built first, and the prison building, with a circular plan, that resembled a bastei called the Cat’s Tail that had previously stood at the site, was built later. The functio-spatial design of the prison assumed placing the cells along the perimeter of the building and included an internal stairwell. The architect planned to combine a traditional masonry structure with modern technology that entailed the use of a cast-iron stairwell and cast-iron cantilevers to support internal platforms. This paper presents this innovative structure, which is the first-ever case of the use of cast iron in a municipal building on this scale in Toruń. The stairs were built from prefabricated elements, whose assembly methods and ornamentation had been a novelty at the time. This subject is a key research problem, especially in the context of the state of preservation of cast-iron stairwells and the disappearing heritage of engineering, as well as conservation challenges.

10

Dynamic properties of hybrid machine tool body - theoretical and experimental investigation

Kępczak Norbert, Pawłowski Witold

Mechanics and Mechanical Engineering

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2021

|

Vol. 25, nr 1

6--14

EN

The article presents theoretical and experimental investigation in order to obtain dynamic properties of hybrid machine tool body in comparison with cast iron body. For this purpose, the theoretical and experimental modal analyses were carried out. The influence of the mineral cast material for filling voids on the dynamic properties of the machine tool body was discussed. During the analysis, the modes and frequencies of free vibrations, the amplitude values and the damping ratios were compared. Despite lowering the free vibration frequency of the hybrid construction, compared to the cast iron body, in some cases, the dynamic propertieswere affected. This could be determined on the basis of decreasing the amplitude value of the transfer function (from 12.16% to 58.66%) and the increasing the vibration damping coefficient ratio (from 12.22% to 75.24%) in the case of a hybrid body as compared to a cast iron body. The final conclusions were drawn about the application of mineral casts in the construction of machine tools and its impact on the dynamic properties of the structure.

11

Ocena nośności zabytkowego słupa żeliwnego wiaty peronowej

Domagała Rafał

Inżynieria i Budownictwo

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2021

|

R. 77, nr 9-10

438--441

PL

Dokonano oceny nośności zabytkowego słupa wiaty peronowej wykonanego z żeliwa szarego perlitycznego z grafitem płatkowym w osnowie perlitycznej EN-GJL-100. Obliczenia wykonano według zbioru norm PN-EN 1993 Eurokod 3.

EN

The load-bearing capacity of a historic platform shed made of gray pearlitic cast iron with EN-GJL-100 pearlitic matrix flake graphite was assessed. The calculations were made according to the set of PN-EN 1993 Eurocode 3 standards.

12

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

|

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.

13

Factors Influencing Cavitation Erosion of NiCrSiB Hardfacings Deposited by Oxy-Acetylene Powder Welding on Grey Cast Iron

Szala Mirosław, Walczak Mariusz, Hejwowski Tadeusz

Advances in Science and Technology. Research Journal

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2021

|

Vol. 15, no 4

376--386

EN

The work presents the results of a study on cavitation erosion (CE) resistance of two NiCrSiB self-fluxing powders deposited by oxy-acetylene powder welding on cast iron substrate grade EN-GJL-200. The mean hardness of deposits A-NiCrSiB, C-NiCrSiB is equal to 908 HV, 399 HV and exceeds those of EN-GJL-200 and X5CrNi18-10 reference specimens 197 HV and 209 HV, respectively. To study CE, the vibratory apparatus has been used and tests were conducted according to the ASTM G32 standard. Cavitation eroded surfaces were examined using a profilometer, optical and scanning electron microscopy. The research indicated that the CE resistance, expressed by the cumulative mass loss decreased in the following order C-NiCrSiB > A-NiCrSiB > X5CrNi18-10 > EN-GJL-200. Therefore, hardfacings were characterised by lower cumulative mass loss, in turn, higher CE resistance than the reference sample and therefore they may be applied as layers to increase resistance to cavitation of cast iron machine components. Results indicate that in the case of multiphase materials, hardness cannot be the main indicator for CE damage prediction while it strongly depends on the initial material microstructure. To qualitatively estimate the cavitation erosion damage (CEd) of NiCrSiB self-fluxing alloys at a specific test time, the following factors should be considered: material microstructure, physical and mechanical properties as well as surface morphology and material loss both estimated at specific exposure time. A general formula for the CEd prediction of NiCrSiB deposits was proposed.

14

Open Atlas of Defects as a Supporting Knowledge Base for Cast Iron Defects Analysis

Sika R., Rogalewicz M., Kroma A., Ignaszak Z.

Archives of Foundry Engineering

|

2020

|

Vol. 20, iss. 1

55--60

EN

A significant development of the foundry industry contributes to the creation of high reliability and operational strength castings so that they meet specific standards in accordance with customers’ needs. This technology, however, is inseparably connected with casting defects in finished products. Cast products are subject to various defects which are considered acceptable or not, which is conditioned by the alloy chemical composition and strength characteristics, that is, generally – qualities to be agreed between the foundry and the customer. It is the latter that led the authors to research on designing a tool enabling the most reliable possible assessment of the emerging casting defects, which after proper consultations can be repaired and the casting – sold. The paper presents an original tool named the Open Atlas of Defects (OAD), developed for the last few years to support the evaluation of cast iron defects using Non-Destructive Testing (NDT) casting defects analysis tools (DCC card – Demerit Control Chart, Pareto-Lorenz analysis and ABC analysis). The OAD tool structure was presented as an integral part of the original system module for acquisition and data mining (A&DM) in conjunction with the possibilities of using selected tools for defect analysis support on the example of cast iron casting.

15

Cause-effect Analysis Using A&DM System for Casting Quality Prediction

Sika R., Ignaszak Z.

Archives of Foundry Engineering

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2020

|

Vol. 20, iss. 2

5--12

EN

The paper indicates the significance of the problem of foundry processes parameters stability supervision and assessment. The parameters, which can be effectively tracked and analysed using dedicated computer systems for data acquisition and exploration (Acquisition and Data Mining systems, A&D systems) were pointed out. The state of research and methods of solving production problems with the help of computational intelligence systems (Computational Intelligence, CI) were characterised. The research part shows capabilities of an original A&DM system in the aspect of selected analyses of recorded data for cast defects (effect) forecast on the example of a chosen iron foundry. Implementation tests and analyses were performed based on selected assortments for grey and nodular cast iron grades (castings with 50 kg maximum weight, casting on automatic moulding lines for disposable green sand moulds). Validation tests results, applied methods and algorithms (the original system’s operation in real production conditions) confirmed the effectiveness of the assumptions and application of the methods described. Usability, as well as benefits of using A&DM systems in foundries are measurable and lead to stabilisation of production conditions in particular sections included in the area of use of these systems, and as a result to improvement of casting quality and reduction of defect number.

16

A New Laser-Registered View of the Shrinkage Kinetics of Foundry Alloys

Zych J., Snopkiewicz T.

Archives of Foundry Engineering

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2020

|

Vol. 20, iss. 3

41--46

EN

This paper presents a new stand for studying the linear shrinkage kinetics of foundry alloys. The stand is equipped with a laser displacement sensor. Thanks to this arrangement, the measurement is of a contactless nature. This solution allows for the elimination of errors which occur in measurements made using intermediary elements (steel rods). The supposition of the expansion (shrinkage) of the sample and the expansion of the heated rod lead to the distortion of the image of the actual dimensional changes of the studied sample. A series of studies of foundry alloys conducted using the new stand allowed a new image of shrinkage kinetics to be obtained, in particular regarding cast iron. The authors introduce in the study methodology a real-time measurement of two linked quantities; shrinkage (the displacement of the free end of the sample) and temperature in the surface layer of the sample casting. This generates not only a classic image of shrinkage (S) understood as S = f (t), but also the view S = f (T). The latter correlation, developed based on results obtained using the contactless method, provide a new, so far poorly known image of the course of shrinkage in foundry alloys, especially cast iron with graphite in the structure. The study made use of hypo- and hypereutectic cast iron in order to generate an image of the differences which occur in the kinetics of shrinkage (as well as in pre-shrinkage expansion - expansion occurs during solidification).

17

Żeliwne płyty brukowe w Warszawie w II poł. XIX w.

Skowron Marek

Przegląd Odlewnictwa

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2019

|

Vol. 69, nr 5-6

132--136

PL

Powszechne zastosowanie żelaza, w tym także żelaza lanego, było jedną z charakterystycznych cech XIX w. Potwierdzeniem tego może być fakt, że dzisiaj okres ten nazywany jest wiekiem żelaza i pary. Żelazo lane, jak dawniej nazywano żeliwo, wykorzystywane było jednak nie tylko w budowie maszyn. Na niespotykaną skalę używane było w budownictwie, a także do wytwarzania przedmiotów gospodarstwa domowego i wyrobów artystycznych. W drugiej połowie XIX w. znalazło jeszcze jedno i to bardzo nietypowe zastosowanie. Były to bowiem elementy... bruku ulicznego, które na masową skalę przez kilkadziesiąt lat były stosowane w Warszawie.

EN

A general application of iron, including cast iron, was one of the characteristic features of the 19th century. This can be confirmed by: the fact, that this period is currently called: The iron and steam age. Cast iron was applied not only in machine building. It was used, on unprecedented scale, in construction engineering and also for producing household items and artistic elements. In the second half of the 19th century it found one more, quite unusual application. These . were elements... of pavements, which on a massive scale were for j several dozen of years, applied in Warsaw.

18

Peculiarities of Alloying Effect on the Eutectic Cementite Behavior Under Hot Rolling

Mironova Tatiana, Proidak Svetlana

New Trends in Production Engineering

|

2019

|

Vol. 2, Iss. 2

289-300

EN

Currently, cast iron remains one of the major modern casting materials in metallurgy and machine-building industry and is sure to take the lead in the future. Chilled cast iron has high hardness and wear resistance due to a large number of carbide phases in its structure. However, low ductility and impact hardness essentially limit its applicability in terms of processing. Hot plastic working, under which the eutectic net crushing is observed, appears to be one of the most effective means of the eutectic alloy products shape and microstructure transformation. Chilled cast iron properties fundamentally improve after hot plastic working: ductility, strength and impact hardness increase by 2-3 times on retention of the high hardness factor. Chilled cast iron ductility increase can be attained when using phase transformations in eutectic cementite under lean alloying with carbide forming elements. The purpose of the paper is to study alloying effect on the chilled cast iron ductility as well as eutectic cementite behavior under hot rolling. In the paper hardening and softening of the structural components in chilled cast iron under hot working have been studied. The deformation texture forming in eutectic cementite under hot rolling has been revealed, which is connected with the dynamic softening and depends on the degree and the nature of its alloying. The mechanism and regularities of the phase transformation effect in cementite on its behavior under plastic deformation and on the alloys ductility in general have been studied. In cementite chromium alloying initiates processes, that can be characterized as the pre-precipitation stage of the new phases, and this way it contributes to the cast iron ductility reduction and embrittles cementite. Carbide transformation, that occurs in eutectic cementite under alloying with vanadium, stimulates softening of the alloy and increases its ductility level. Moreover, the multiple glide planes {130},{011},{112} in cementite have been determined. It has been found out, that in supersaturated cementite vanadium carbides precipitation stimulates the extra glide plane {111} occurrence under hot rolling. The essence of the carbide transformation phenomenon is that under hot working there occurs the lubricating effect at the transition of the metastable iron carbide condition, which is strengthened with vanadium supersaturation and mechanical hardening, to a more stable condition due to precipitation of the proeutectoid constituents on the one hand, and because of the dynamic softening processes on the other hand. At that, the autocatalyticity effect is observed: there is precipitation of carbides with hardening and softening, similar to the processes that arise as a result of the superplastic effect induced by phase transformations.

19

The Influence of Lamellar Graphite Cast Iron Annealing on Hardness and Structure

Roučka J., Prochazka J., Kana V., Krutis V., Nedelova K.

Archives of Foundry Engineering

|

2019

|

iss. 4

105--112

EN

An analysis has been carried out of the influence of annealing time at the preheating temperature of 650 °C on the change in hardness and alloy structure of lamellar graphite cast iron in the working as well as in the laboratory conditions. This preheat temperature is common during reclaiming welding of castings with complex shapes. The changes in unalloyed cast iron EN-GJL 200 to EN-GJL 300 according to ISO 1690 standard and cast iron with low amount of elements such as Sn, Cu, Cr, and Mo and their combinations were assessed. It was found that the cast iron of higher strength grades has better hardness and structural stability. Cast iron alloyed with chromium or its combinations has the highest stability. In unalloyed cast iron, a partial degradation of pearlite occurs; in alloyed cast iron the structural changes are not conclusive.

20

Multiparameter Assessment of the Gas Forming Tendency of Foundry Sands with Alkyd Resins

Mocek J.

Archives of Foundry Engineering

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2019

|

iss. 2

41--48

EN

Gas atmosphere at the sand mould/cast alloy interface determines the quality of the casting obtained. Therefore the aim of this study was to measure and evaluate the gas forming tendency of selected moulding sands with alkyd resins. During direct and indirect gas measurements, the kinetics of gas evolution was recorded as a function of the temperature of the sand mixture undergoing the process of thermal destruction. The content of hydrogen and oxygen was continuously monitored to establish the type of the atmosphere created by the evolved gases (oxidizing/reducing). The existing research methodology [1, 7, 8] has been extended to include pressure-assisted technique of indirect measurement of the gas evolution rate. For this part of the studies, a new concept of the measurement was designed and tested. This article presents the results of measurements and compares gas emissions from two sand mixtures containing alkyd resins known under the trade name SL and SL2002, in which the polymerization process is initiated with isocyanate. Studies of the gas forming tendency were carried out by three methods on three test stands to record the gas evolution kinetics and evaluate the risk of gas formation in a moulding or core sand. Proprietary methods for indirect evaluation of the gas forming tendency have demonstrated a number of beneficial aspects, mainly due to the ability to record the quantity and composition of the evolved gases in real time and under stable and reproducible measurement conditions. Direct measurement of gas evolution rate from the tested sands during cast iron pouring process enables a comparison of the results with the results obtained by indirect methods.