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1
Content available The Effect of Sulphur Content on the Microstructure of Vermicular Graphite Cast Iron
Mróz M., Orłowicz A. W., Tupaj M., Lenik M., Kawiński M., Kawiński M.
Archives of Foundry Engineering
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2022
|
Vol. 22, iss. 1
18--22
EN
The application of ferritic-matrix vermicular graphite cast iron in the production of fireplace fireboxes improves their thermal output, but the consumer market for these products prioritises their price. Given this consideration, this work concerns a comparison of the quality of vermicular graphite cast iron types produced from 0.025%S pig iron (a less expensive material) and 0.010%S pig iron (a more expensive material) in terms of the number and shape of vermicular graphite precipitates varying with the magnesium level in the alloy. It turned out that the vermicular graphite cast iron made with the 0.025%S pig iron demonstrated a slightly lower number of vermicular graphite precipitates. For both vermicular graphite cast iron melts, 0.028%Mg and 0.020%Mg in the alloys provided a vermicular graphite precipitate share of approx. 50% and 95%, respectively.
2
Content available Influence of Microstructure and Heat Transfer Surface on the Thermal Power of Cast Iron Heat Exchangers
Mróz M., Orłowicz A. W., Tupaj M., Lenik M., Kawiński M. J., Kawiński M.
Archives of Foundry Engineering
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2021
|
Vol. 21, iss. 4
93--96
EN
The paper presents the results of calorimetric tests of segment elements of fireplace inserts. The aim of the work was to optimize their thermal power by replacing the previously used gray cast iron with flake graphite with gray iron with vermicular graphite and replacing the existing geometry of the heat transfer surface with a more developed one. It turned out that the thermal power of the test segments made of cast iron with vermicular graphite was higher compared to the segments of the same shape made of gray cast iron with flake graphite. It was found that the use of segments made of vermicular cast iron with a ferritic matrix allowed for an increase in the thermal power value by dozen percent, compared to segments of the same shape made of vermicular cast iron with a pearlitic matrix. The test results showed that the thermal power of the test segments depends on the variant of the development of both the heat receiving surface and the heat giving off surface. The highest value of the thermal power was obtained when ribbing in the form of a lattice was used on both of these surfaces, and the lowest when using flat surfaces.
3
Content available Ultrasonic Testing of Vermicular Cast Iron Microstructure
Tupaj M., Orłowicz A. W., Mróz M., Kupiec B., Pająk D., Kawiński M.
Archives of Foundry Engineering
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2020
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Vol. 20, iss. 4
36--40
EN
The paper presents results of a study on the effect of passage of time on magnesium content in iron alloys and the effect of magnesium content on the number of vermicular graphite precipitations per unit surface area and value of the longitudinal ultrasonic wave velocity for two different vermicularization methods. The study was carried out with the use of inspection bar castings. For specific production conditions, it has been found that in case of application of both the cored wire injection method and the method of pouring liquid metal over magnesium master alloy on ladle bottom, the satisfactory level of magnesium content in the bottom-pour ladle, for which it was still possible to obtain castings with vermicular graphite, was 0.018% Mg. In case of the cored wire injection method, the “time window” available to a pouring station at which castings of vermicular cast iron are expected to be obtained, was about 5 minutes. This corresponds to the longitudinal ultrasonic wave velocity values exceeding 5500 m/s and the number of graphite precipitations per unit surface area above 320 mm-2. In case of the master alloy method, the respective “time window” allowing to obtain castings of vermicular cast iron was only about 3 minutes long. This corresponds to the longitudinal ultrasonic wave velocity value above 5400 m/s and the number of graphite precipitations per unit surface area above 380 mm-2.
4
Content available The Effect of Structure on Thermal Power of Cast-iron Heat Exchangers
Mróz M., Orłowicz A. W., Tupaj M., Jacek-Burek M., Radoń M., Kawiński M.
Archives of Foundry Engineering
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2020
|
Vol. 20, iss. 1
27--30
EN
The objective of the study reported in this paper was to determine the effect of structure on thermal power of cast-iron heat exchangers which in this case were furnace chambers constituting the main component of household fireplace-based heating systems and known commonly as fireplace inserts. For the purpose of relevant tests, plate-shaped castings were prepared of gray iron with flake graphite in pearlitic matrix (the material used to date typically for fireplace inserts) as well as similar castings of gray cast iron with vermicular graphite in pearlitic, ferritic-pearlitic, and ferritic matrix. For all the cast iron variants of different structures (graphite precipitate shapes and matrix type), calorimetric measurements were carried out consisting in determining the heat power which is quantity representing the rate of heat transfer to the ambient environment. It has been found that the value of the observed heat power was affected by both the shape of graphite precipitates and the type of alloy matrix. Higher thermal power values characterize plate castings of gray iron with vermicular graphite compared to plates cast of the flake graphite gray iron. In case of plates made of gray cast iron with vermicular graphite, the highest values of thermal power were observed for castings made of iron with ferritic matrix.
5
Content available Ductile Cast Iron Microstructure Adjustment by Means of Heat Treatment
Mróz M., Orłowicz A. W., Tupaj M., Kupiec B., Kawiński M.
Archives of Foundry Engineering
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2020
|
Vol. 20, iss. 3
37--40
EN
The study presented in this paper concerned the possibility to apply a heat treatment process to ductile cast-iron thin-walled castings in order to remove excessive quantities of pearlite and eutectic cementite precipitates and thus meet the customer’s requirements. After determining the rates of heating a casting up to and cooling down from 900°C feasible in the used production heat treatment furnace (vh = 300°C/h and vc = 200°C/h, respectively), dilatometric tests were carried out to evaluate temperatures Tgr, TAc1 start, TAc1 , TAr1 start, and TAr1 end. The newly acquired knowledge was the base on which conditions for a single-step ferritizing heat treatment securing disintegration of pearlite were developed as well as those of a two-step ferritization process guaranteeing complete disintegration of cementite and arriving at the required ferrite and pearlite content. A purely ferritic matrix and hardness of 119 HB was secured by the treatment scheme: 920°C for 2 hours / vc = 60°C/h / 720°C for 4 hours. A matrix containing 20–45% of pearlite and hardness of 180–182 HB was obtained by applying: 920°C for 2 hours or 4 hours / vc = 200°C/h to 650°C / ambient air.
6
Content available Improvement of Operating Performance of a Cast-Iron Heat Exchanger by Application of a Copper Alloy Coating
Mróz M., Orłowicz A. W., Tupaj M., Jacek-Burek M., Radoń M., Kawiński M.
Archives of Foundry Engineering
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2019
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iss. 3
84--87
EN
The paper deals with possibility to improve operating performance of cast-iron heat exchangers by providing them with a copper alloy (CuTi2Cr) with the use of the flame spraying method. A test exchanger was cast of a gray cast iron with vermicular graphite in ferritic-pearlitic matrix obtained in production conditions at KAW-MET Iron Foundry with the wire method used to vermicularize the material. The test samples were two plates cast in sand molds, of which one was given a flame-sprayed CuTi2Cr coat on one side. The operating performance of such model cast-iron heat exchangers, with and without CuTi2Cr coating, was tested on a set-up for determining the heat flow rate (thermal power) transferred by the heat exchanger to environment. The obtained results indicate that the value of the heat flow rate characterizing the CuTi2Cr-coated cast-iron heat exchanger was by 10% higher compared to the flow rate of heat conveyed to environment by the heat exchanger without coating.
7
Content available Improvement of Al-Si Alloy Fatigue Strength by Means of Refining and Modification
Tupaj M., Orłowicz A. W., Trytek A., Mróz M.
Archives of Foundry Engineering
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2019
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iss. 4
61--66
EN
The paper presents results of a study concerning an AlSi7Mg alloy and the effect of subjecting the liquid metal to four different processes: conventional refining with hexachloroethane; the same refining followed by modification with titanium, boron, and sodium; refining by purging with argon carried out in parallel with modification with titanium and boron salts and strontium; and parallel refining with argon and modification with titanium, boron, and sodium salts. The effect of these four processes on compactness of the material, parameters of microstructure, and fatigue strength of AlSi7Mg alloy after heat treatment. It has been found that the highest compactness (the lowest porosity ratio value) and the most favorable values of the examined parameters of microstructure were demonstrated by the alloy obtained with the use of the process including parallel purging with argon and modification with salts of titanium, boron, and sodium. It has been found that in the fatigue cracking process observed in all the four variants of the liquid metal treatment, the crucial role in initiation of fatigue cracks was played by porosity. Application of the process consisting in refining by purging with argon parallel to modification with Ti, B, and Na salts allowed to refine the microstructure and reduce significantly porosity of the alloy extending thus the time of initiation and propagation of fatigue cracks. The ultimate effect consisted in a distinct increase of the fatigue limit value.
8
Content available The Effect of Surface Texture of Steel Disc on Friction and Fretting Wear
Lenart A., Pawlus P., Dzierwa A., Tupaj M.
Tribologia
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2018
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nr 4
39--48
EN
Fretting tests were performed using an Optimol SRV5 tribotester in a ball-on-flat scheme. Balls from 100Cr6 steel of 60 HRC hardness and diameters of 10 mm co-acted with discs from 42CrMo4 steel of 47 HRC hardness under dry gross fretting conditions. Tests were performed at 30°C and 25–35% relative humidity, and the number of cycles was 18000. During each test, the normal load was kept constant. Six sets of experiments were conducted. Discs had different surface textures as the result of machining. It was found that the lowest coefficients of friction were obtained for anisotropic surfaces when ball movements were perpendicular to main disc texture directions.
PL
W badaniach zastosowano tester tribologiczny Optimol SRV5. Kulka ze stali 100Cr6 o twardości 60 HRC kontaktowała się z tarczą o średnicy 10 mm wykonaną ze stali 42CrMo4 o twardości 47 HRC w warunkach frettingu. Temperatura wynosiła 30°C, wilgotność względna 25–35% przy liczbie cykli równej 18000. Tarcze charakteryzowały się zróżnicowaną strukturą geometryczną powierzchni uzyskaną w wyniku obróbki. Najmniejsze współczynniki tarcia osiągnięto, kiedy ruch kulki odbywał się prostopadle do głównego kierunku ukształtowania powierzchni tarczy.
9
Content available remote Odporność na korozję powłoki NiCrFeSi obciążonej cieplnie w atmosferze powietrza i w środowisku siarki
Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Kupiec B., Radoń M., Jacek M.
Przegląd Spawalnictwa
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2018
|
R. 90, nr 4
73--75
PL
Praca dotyczy natryskiwanej plazmowo powłoki NiCrFeSi na podłoże ze stali kotłowej (P 250GH). Powłokę obciążano cieplnie w atmosferze powietrza i w środowisku siarki. Obciążenie cieplne wynosiło 2000 cykli. Jeden cykl obejmował: nagrzewanie do temperatury 560 °C i wygrzewanie w tej temperaturze w czasie 3 minut, chłodzenie do temperatury 300 °C, nagrzewanie do 560 °C i wygrzewanie w tej temperaturze w czasie 1,5 minuty oraz chłodzenie do temperatury 150 °C. Efektem obciążeń cieplnych było zmniejszenie grubości powłoki o 39 μm. Stwierdzono, że siarka dyfundowała w warstwę przypowierzchniową. Tworzące się produkty jej reakcji z niklem i chromem sprzyjały wykruszaniu się składników tej warstwy, które następnie ulegały utlenianiu.
EN
The paper deals with a NiCrFeSi coating plasma-sprayed on a boiler steel (P 250GH) substrate. The coating was heat-loaded in atmosphere of air and in sulfur environment. The heat load comprised 2000 cycles, whereas each of the cycles included: heating up to 560 °C and soaking at the temperature for 3 minutes; cooling down to 300 °C and soaking at the temperature for 1.5 minutes; and cooling down to 150 °C. As a result of such thermal cycling, thickness of the coating was reduced by 39 μm. It has been found that sulfur had diffused into the superficial layer. The occurring products of sulfur reacting with chromium and nickel contributed to spalling of components of the layer which subsequently were subject to oxidation.
10
Content available The Effect of the Heat Flux Density on Microstructure of Surface Remeltings on C355 Alloy Castings
Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Jacek M., Radoń M.
Archives of Foundry Engineering
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2018
|
Vol. 18, iss. 2
35--38
EN
The paper presents results of a study on the effect of the flux density of heat carried away for the remelting area to substrate in the course of surface remelting with concentrated heat stream on values of structural parameters λ1D and λ2D of α(Al) phase dendrites in C355 alloy. The remeltings were made with the use of GTAW method, at arc current intensity I = 200 A and concentrated heat stream scanning speed vs = 200, 400, 600, and 800 mm/min. The used protective gas was argon supplied at rate of 20 l/min. It has been found that the increase of the rate of scanning with concentrated heat stream results in a change of the remelting-substrate separation surface shape consisting in reduction of the remelting width and depth. This increases the value of the flux density of heat transmitted from the remelting area to substrate which in turn acts in favor of reduction of structural parameters λ1D and λ2D characterizing α(Al) phase dendrites in C355 alloy.
11
Content available Morphology and Material Properties of Carbides in High (24%) Chromium Cast Iron
Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Jacek M., Radoń M.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 1
77--80
EN
The present paper is a presentation of results of a study on morphology, chemical composition, material properties (HVIT, HIT, EIT), and nanoindentation elastic and plastic work for carbide precipitates in chromium cast iron containing 24% Cr. It has been found that the carbides differ in chemical composition, as well as in morphology and values characterizing their material properties. The carbides containing the most chromium which had the shape of thick and long needles were characterized with highest values of the analyzed material properties.
12
Content available Improvement of Resistance of Cast-iron Heat Exchangers to High-temperature Corrosion
Orłowicz A. W., Tupaj M., Trytek A., Mróz M., Radoń M., Jacek M.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 3
49--52
EN
The paper discusses the possibility of improving resistance of heat exchangers made of gray cast iron with flake graphite to high-temperature corrosion by providing them with metallic coatings. A metallic coating containing 76.9% Ni, 19.8% Cr, 1.7% Si, 0.9% Fe, and 0.9% Mn was applied by means of the plasma spraying method and subjected to cyclically variable thermal loads in the atmosphere of solid fuels combustion products (oxygen, sulfur, chlorine, and sodium). In a 30-day thermal load test held at temperature 500°C it has been found that thickness of the metallic coating decreased from the initial (240 ± 6) μm to (231 ± 6) μm. The depth to which sulfur, chlorine, and sodium penetrated the coating was about 30 μm. Increased oxygen content occurred along the whole coating depth. In the coating area adjacent to the substrate surface, the content was twice as high compared to this observed in the initial coating material. Although presence of oxygen was found within the whole depth of the coating, i.e. (231 ± 6) μm, no signs of susceptibility of the sprayed metallic layer to separation from substrate of gray cast iron with flake graphite were found.
13
Content available A Possibility to Improve Resistance of Cast-iron Wood Chip Fine Grinder Liners to Abrasive Wear
Orłowicz A. W., Mróz M., Tupaj M., Kupiec B., Jacek M., Radoń M.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 4
35--38
EN
The paper deals with the issue of potential for improvement of resistance of wood chip fine grinders to abrasive wear by providing them with WCCoCr coating applied with the use of atmospheric plasma spraying (APS). The study focused on establishing parameters of the technological process of spraying a 250–270 μm thick coating onto surface of ductile cast iron castings used to date as grinder linings. The presented data include results of microstructure examination, chemical composition analysis, HV hardness measurements, and scratch tests for both previous and new variant of linings. The obtained scratch test results indicate that the material of the coating is characterized with definitely lower susceptibility to scratching. The scratch made on coating was 75–84 μm wide and 7.2–8.2 μm deep, while the scratch on cast iron was distinctly wider (200–220 μm) and deeper (8.5–12.8 μm). In case of cast iron, the range of variability in scratch width and depth was definitely larger. This can be explained with large difference in hardness of individual components of microstructure of cast iron and significantly larger plastic deformation of cast iron compared to the coating revealed in the course of indenter motion over surfaces of the two materials. It has been found that application of WCCoCr coating offered better resistance of lining surfaces to scratching which can be considered a rationale for undertaking in-service tests.
14
Content available A Possibility to Improve Resistance of Cast-iron Hydraulic Valves to Cavitation Wear
Orłowicz A. W., Tupaj M., Mróz M., Kupiec B., Jacek M., Radoń M.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 4
31--34
EN
A common problem encountered in hydraulic valves is a progressing deterioration of tightness of their water flow cutting-off seats. The seats are provided usually with a copper-alloy insert joined mechanically with cast-iron valve housing. The problem of unreliability of such joints can be solved by providing surface of the seat with a coating, deposited with the use of HVOF method and resistant to abrasive and cavitation wear. The tests were carried out for a sealing-draining seat insert made of CuZn39Pb2Al brass used to date and a specimen taken from the cast-iron valve housing which was the substrate for a plasma-sprayed coating of powder containing 86.1% Cr, 7.2% Ni, and 6.7% C. The coating, 345 ± 15 μm thick, was characterized with good quality of bonding with cast-iron substrate and high compactness of the material. The cavitation wear test on materials used in the study were carried out with the use of Vibra-Cell ultrasonic liquid processor (Sonics) equipped with a piezoelectric probe operating at the frequency of 20 kHz. Based on profilograms taken along a line crossing centers of cavitation craters, measurements of the height parameter Rt, and microscopic observations of surfaces it has been found that the coating plasma-sprayed onto substrate of nodular cast iron demonstrated higher resistance to cavitation compared to copper-alloy inserts used so far in cast-iron hydraulic valves. Cavitation craters on the material used typically for valve seats to date were more distinctly outlined and deeper compared to craters observed on the coating. Larger were also sizes of local tear-outs which resulted in larger difference between the peaks line and the valleys line.
15
Content available Cavitation Erosion of Nodular Cast Iron - Microstructural Effects
Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Jacek M., Radoń M.
Archives of Foundry Engineering
|
2017
|
Vol. 17, iss. 4
119--122
EN
The paper deals with susceptibility of nodular cast iron with ferritic-pearlitic matrix on cavitation erosion. Cavitation tests were carried out with the use of a cavitation erosion vibratory apparatus employing a vibration exciter operated at frequency of 20 kHz. The study allowed to determine the sequence of subsequent stages in which microstructure of cast iron in superficial regions is subject to degradation. The first features to be damaged are graphite precipitates. The ferritic matrix of the alloy turned out to be definitely less resistant to cavitation erosion compared to the pearlitic matrix component.
16
Content available Usable Properties of AlSi7Mg Alloy after Sodium or Strontium Modification
Tupaj M., Orłowicz A. W., Mróz M., Trytek M., Markowska O.
Archives of Foundry Engineering
|
2016
|
Vol. 16, iss. 3
129--132
EN
The paper deals with the effect of microstructure diversified by means of variable cooling rate on service properties of AlSi7Mg cast alloy refined traditionally with Dursalit EG 281, grain refining with titanium-boron and modified with sodium and a variant of the same alloy barbotage-refined with argon and simultaneously grain refining with titanium-boron and modified with strontium. For both alloy variants, the castings were subject to T6 thermal treatment (solution heat treatment and artificial aging). It turned out that AlSi7Mg alloy after simultaneous barbotage refining with argon and grain refining with titanium-boron and modified with strontium was characterised with lower values of representative microstructure parameters (SDAS – secondary dendrite arm spacing, λE, lmax) and lower value of the porosity ratio compared to the alloy refined traditionally with Dursalit EG 281 and grain refining with titanium-boron and modified with sodium. The higher values of mechanical properties and fatigue strength parameters were obtained for the alloy simultaneously barbotage-refined with argon and grain refining with titanium-boron and modified with strontium.
17
Content available The Effect of Cooling Rate on Properties of Intermetallic Phase in a Complex Al-Si Alloy
Tupaj M., Orłowicz A. W., Mróz M., Trytek A., Markowska O.
Archives of Foundry Engineering
|
2016
|
Vol. 16, iss. 3
125--128
EN
The cooling rate is one of the main tools available to the process engineer by means of which it is possible to influence the crystallisation process. Imposing a desired microstructure on a casting as early as in the casting solidification phase widens significantly the scope of technological options at disposal in the process of aluminium-silicon alloy parts design and application. By changing the cooling rate it is possible to influence the course of the crystallisation process and thus also the material properties of individual microstructure components. In the study reported in this paper it has been found that the increase of cooling rate within the range of solidification temperatures of a complex aluminium-silicon alloy resulted in a decrease of values of the instrumented indentation hardness (HIT) and the instrumented indentation elastic modulus (EIT) characterising the intermetallic phase occurring in the form of polygons, rich in aluminium, iron, silicon, manganese, and chromium, containing also copper, nickel, and vanadium. Increased cooling rate resulted in supersaturation of the matrix with alloying elements.
18
Content available The Effect of Carbides Orientation in NC11 Steel on Scratch Susceptibility of Die Inserts Used to Press Stampings for Refractory Shapes
Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Kupiec B., Korzeniowski M., Sondej K., Kozak L.
Archives of Foundry Engineering
|
2016
|
Vol. 16, iss. 2
95--98
EN
NC11 steel, in view of the specificity of its manufacturing process, is characterised with band-like orientation of carbides. Depending on the direction of cutting the material for the inserts out of commercially available steel products, carbide bands can be oriented in parallel or perpendicularly to the direction in which aggregate grains move in the process of pressing stampings. It has been found that in case of scratches made in direction perpendicular to carbide bands, depth of the scratches is less than this observed when scratches are made in direction coinciding with prevailing orientation of carbide precipitates.
19
Content available The Effect of a Thin-Wall Casting Mould Cavity Filling Conditions on the Casting Surface Quality
Trytek A., Orłowicz A. W., Tupaj M., Mróz M., Markowska O., Bąk G., Abram T.
Archives of Foundry Engineering
|
2016
|
Vol. 16, iss. 4
222--226
EN
The paper presents results of metallographic examination of faults occurring in the course of founding thin-walled cast-iron castings in furan resin sand molds. A non-conformance of the scab type was Observed on surface of the casting as well as sand buckles and cold shots. Studied the chemical composition by means of a scanning electron microscope in a region of casting defects: microanalysis point and microanalysis surface. Around the observed defects discloses high concentration of oxides of iron, manganese and silicon. A computer simulation of the casting process has been carried out with the objective to establish the cause of occurrence of cold shots on casting surface. The simulation was carried out with the use of NovaFlow & Solid program. We analyzed the flowing metal in the mold cavity. The main reason for the occurrence of casting defects on the surface of the casting was gating system, which caused turbulent flow of metal with a distinctive splash stream of liquid alloy.
20
Content available On Degradation of Cast Iron Surface - Protective Paint Coat Joint
Tupaj M., Orłowicz A. W., Mróz A., Bąk G., Abram T.
Archives of Foundry Engineering
|
2016
|
Vol. 16, iss. 3
133--136
EN
The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells.
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