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1

Structure and mechanical properties of cermet Ni-Al/MSZ thick coating prepared by flame spraying technique

Saleh Mahmood M., Khemakhem Hamadi, Jassim Ismel K., Al-Saqa Read Hashim

Ochrona przed Korozją

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2024

|

nr 1

9--14

EN

The aim of this study was to obtain a thick protective cermet coating on API 5L (carbon steel) pipes, used in the oil industry. A new method involving flame spray coating has been selected to produce thick ceramic-metal coatings of Ni-Al/MgO-ZrO2 under optimal spraying parameters. Structural properties were measured by X-ray diffraction (XRD). Morphology was determined by means of scanning electron microscopy (SEM). The elemental composition in the cermet coating was confirmed by energy dispersive spectroscopy (EDS). Deposition efficiency was found to be an important factor as demonstrated by adhesion force results obtained using the pull-out tensile test. The results show that the best spray distance is 20 cm, as it ensures good interaction between the layers, a high adhesion force value of 8.4 MPa, a uniform microstructure, low porosity, a hardness of 166.4 HV, and a coating thickness of approximately 1.85 mm. X-ray results clearly show that the cermet coating consists of numerous phases, such as tetragonal (T), monoclinic, and face center cubic (FCC). SEM images revealed that the typical particle-containing microstructures consisted of spherical shapes with elongated agglomerations. Finally, based on the results obtained, it can be concluded that flame spray coating provides a significant improvement in performance.

PL

Celem pracy było uzyskanie grubej ochronnej powłoki cermetalowej na rurach API 5L (ze stali węglowej), stosowanych w przemyśle naftowym. Wybrano nową metodę natryskiwania płomieniowego w celu wytworzenia grubych powłok ceramiczno-metalowych Ni-Al/MgO-ZrO2 przy optymalnych parametrach natryskiwania. Właściwości strukturalne zostały zmierzone za pomocą dyfrakcji rentgenowskiej (XRD). Morfologię określono za pomocą skaningowej mikroskopii elektronowej (SEM). Skład pierwiastkowy powłoki cermetalowej ustalono, używając spektroskopii dyspersji energii (EDS). Stwierdzono, że wydajność osadzania jest ważnym czynnikiem, o czym świadczą wyniki pomiaru siły adhezji uzyskane w próbie rozciągania. Z badań wynika, że najlepsza odległość natryskiwania wynosi 20 cm – zapewniona jest wówczas dobra interakcja między warstwami, wysoka wartość siły adhezji: 8,4 MPa, jednolita mikrostruktura, niska porowatość, twardość wynosi 166,4 HV, a grubość powłoki ok. 1,85 mm. Badania rentgenowskie pozwoliły ustalić, że powłoka cermetalowa składa się z wielu faz: tetragonalnej (T), jednoskośnej i FCC. Obrazy SEM ujawniły, że typowe mikrostruktury zawierające cząstki składały się z kulistych struktur tworzących wydłużone aglomeracje. Na podstawie uzyskanych wyników można stwierdzić, że zastosowana metoda natryskiwania płomieniowego zapewnia znaczną poprawę właściwości ochronnych.

2

Application of regression models on the prediction of corrosion degradation of a crude oil distillation unit

Varbai Balázs, Wéber Richárd, Farkas Balázs, Danyi Péter, Krójer Antal, Locskai Roland, Bohács György, Hős Csaba

Advances in Materials Science

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2024

|

Vol. 24, nr 1(79)

72--85

EN

The crude distillation unit is the most critical elements in the refining process. Moreover, most of the equipment in the distillation unit are made of general carbon steels. Data analysis models, machine learning techniques can predict corrosion degradation rates. We used Pearson’s correlation coefficient and multiple linear regression, to predict the impact of process parameters. Altogether, we have analysed 84 channels of technological parameters, and 22 different types of crude oils. Among the corrosion agents, the chloride content strongly affected the weight loss of coupons, where the highest coefficient was 0.68. The most influential parameter is found to be the pH value. Thus, an estimation method of the pH value is set up to predict the corrosion degradation rate. The regression correlation for estimating the pH value is 0.53 if the corrosion agents are not used, which can be improved to 0.76 if the corrosion agents are also used in the regression analysis.

3

Influence hot plastic deformation on the structure and properties of carbon steel of the railway wheel

Vakulenko Igor, Plitchenko Sergey, Bolotova Dariy, Asgarov Khangardash

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2023

|

z. 121

257--266

EN

The study is devoted to the explanation of the influence of hot plastic deformation on the properties of railway wheels. The shape of individual elements of the wheel provides for a different degree of hot compression, which determines the mechanism for the development of the recrystallization at austenite. With a decrease in the degree of the hot deformation, a certain proportion of grains with a low energy of linear stretching are formed in austenite. As a result, of the low mobility of such boundaries, the likelihood of preservation of part of the substructural state of the austenite increases, which should affect the formation of a colony of perlite during the cooling of the carbon steel. Against background preservation and a dependence of strength properties on the dispersion of the pearlite colony, the appearance in austenite of grain boundaries with a low energy of linear tension leads to a qualitative change in the plastic properties of railway wheel steel. The increase in plasticity of carbon steel with an increase in dispersion of the pearlite colony is due to a decrease in the effect of solid solution hardening and an increase in the role of the ferrite-cementite interface in the development processes of strain hardening carbon steel. The results obtained can be useful for improving the technology of manufacturing all-rolled railway wheels.

4

XRD and STA Characterization of Phosphate Layers Deposited on the Carbon Steel Surface

Burduhos-Nergis Diana Petronela, Bejinariu Costica, Cazac Alin Marian, Sandu Andrei Victor, Vizureanu Petrica

Archives of Metallurgy and Materials

|

2023

|

Vol. 68, iss. 3

955--960

EN

Carbon steel is one of the most widely used alloys in many industries, however, its use is limited by its low corrosion resistance. Depositing a layer of phosphate on its surface improves the corrosion resistance as well as other properties, such as wear resistance, adhesion etc. Accordingly, preliminary studies demonstrated that carbon steel coated with phosphate layers can be used in the manufacture of carabiners for various fields: civil engineering, oil industry etc. Whereas, to demonstrate their capacity to operate in severe conditions related to fire rescue and extinguishing operations, it is necessary to evaluate the thermal behaviour of these materials. Thus, the main goal of this paper is to study the behaviour at high temperatures of three different types of phosphate layers deposited on carbon steel surface, by STA analysis. Also, the paper aims to study the formation of different phosphate layers by determining the types of compounds formed after the completion of the phosphating process, by XRD analysis.

5

Microstructure and Mechanical Properties of AISI 1106 /AISI 1045 Steels Drawn Arc Stud Welded Joints

Algodi Samer Jasim, Salman Abdulhakeem Amer, Al-helli Ali H.

Advances in Science and Technology. Research Journal

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2023

|

Vol. 17, no 5

48--55

EN

Arc stud welding process was used to join a fully threaded low carbon steel AISI 1106 stud to medium carbon steel AISI 1045 plate, the effects of welding current 200, 400 A and the welding time 0.1 to 0.6 step 0.1 s on the microstructure and mechanical properties were investigated, additional parameters of adding 0.1, 1 g SiC powder and applying nano carbon layer to the welding area also included. The results demonstrate that the preferred stud welding process parameters for this system was 400 A with 0.4 s welding current and time, respectively, which has a maximum tensile strength of 583 MPa. The joints fabricated with ash and nano carbon coated at preferred welding parameters showed a slight reduction in tensile strength. The fracture of the tensile test specimen consists of three failure modes including of interface fracture between stud and plate surface due to incomplete melting at low processing parameter, pullout fracture which is featured by a hole in the plate surface and fracture at the stud shank instead of the weldment interface or heat affected zone. The microstructure of the stud and plate are characterized by equiaxed grain of ferrite and pearlite with small amount of ferrite, respectively. The fusion zone consists of fine grain of ferrite and perlite. The hardness of the fusion zone was recording 132 HV which it slightly higher than the stud hardness 128 HV and lower than that of plate of 164 HV.

6

Influence structure on the plasticity of carbon steel of the railway wheel rim in operation

Vakulenko Igor Alex, Vakulenko Leonid, Bolotova Dariy, Kurt Bulent, Asgarov Hangardash, Çölova Ömer

Zeszyty Naukowe. Transport / Politechnika Śląska

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2022

|

z. 115

183--192

EN

When simulating the operating conditions of the rim of a railway wheel, an analysis of change in the structural state from the possible degree of plastic deformation and the heating temperature of steel near the rolling surface was carried out. The development processes of spheroidization and coalescence of cementite during heating of the cold-worked steel change its ability to strain hardening. Substructure changes during heating to temperatures of 500-550°C deformed steel are accompanied by a simultaneous decrease in its ability to strain hardening and the level of plasticity. When heated above 500-550°C, the development of ferrite recrystallization processes provides a gradual transition of the metal from substructure hardening to hardening from grain boundaries with large angles of disorientation. It is shown that regardless of the nature of the main structural element, the ability of steel to strain hardening and the level of plasticity after heating are related by a proportional relationship.

7

Influence of Adhesive Compound Viscosity on the Strength Properties of 1.0503 Steel Sheets Adhesive Joints

Miturska-Barańska Izabela, Rudawska Anna

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

196-205

EN

The presented study concerned the comparison of the adhesive joints strengths of 1.0503 carbon steel sheets of higher quality, which were made using adhesive compounds characterized by different viscosity index of the components. Three types of commercial epoxy resins were used: Epidian 5, Epidian 53 and Epidian 57, as well as two types of curing agents: polyamide (PAC) and amine (Z-1). The surfaces of the test specimens were subjected to a pre-treatment operation in the process of a mechanical machining with an abrasive coated tool of P320 gradation. The surface roughness measurements were carried out as a control. The single-lap adhesive joints were the subject of the strength testing. The strength tests carried out on a Zwick/Roell Z150 testing machine concerned the comparison of the strength of the adhesive joints loaded in shear. Statistical analysis was performed on the results obtained. It was observed, among others, that the adhesive joints prepared with the epoxy adhesive compounds containing the polyamide curing agent showed much higher the shear strength than the adhesive joints made with the epoxy adhesive compounds containing the amine curing agent. Moreover, the use of the polyamide curing agent in the adhesive compounds with the epoxy resins resulted in formation of a more elastic adhesive layer, for which higher elongation was observed than in the case of the epoxy compound with the amine curing agent.

8

Effect of addition of non-functionalized graphene oxide in a commercial epoxy resin used as coating

Varela Caselis Jenaro Leocadio, Santamaría Juárez Juana Deisy, Galicia Aguilar José Alberto, Domínguez Alcalá María Fernanda, Rubio Rosas Efraín, Mendoza Hernández José Carlos, Sánchez Cantú Manuel

Materials Science Poland

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2021

|

Vol. 39, No. 4

467--477

EN

The paper studies the effect of incorporating graphene oxide (GO) without surface functionalization on a commercial epoxy resin. GO was dispersed in a commercial epoxy resin at concentrations of 0 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, and 3 wt.%. The resultant materials were deposited on carbon steel substrates, followed by the use of a 5 wt.% aqueous NaCl electrolyte, to evaluate the effectiveness of their anticorrosive coating function. Scanning electron microscopy (SEM) analysis showed that the GO was homogenously dispersed in the polymer matrix, resulting in flat and smooth surfaces. The X-ray diffraction (XRD) results showed that although GO was highly dispersed in the polymer matrix, multilayer graphene was also obtained after curing. The anticorrosive properties were evaluated by electrochemical impedance spectroscopy (EIS) at various exposure periods. Analysis of the prepared samples indicated that the best anticorrosion performance among them was available with the 0.5 wt.% GO coating. The obtained results indicate that GO–polymer matrix composites provide improved corrosion protection properties even after 500 h exposure to the NaCl solution.

9

Model wymiany ciepła w procesie ciągłego odlewania stali z uwzględnieniem lokalnego warunku brzegowego

Rywotycki Marcin, Hadała Beata, Malinowski Zbigniew

Hutnik, Wiadomości Hutnicze

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2021

|

Vol. 88, nr 3-4

19--22

PL

W pracy przedstawiono obliczenia symulacyjne pola temperatury wykonane dla wlewka płaskiego ze stali węglowej. Modelowano proces ciągłego odlewania pasma o szerokości 1500 mm i wysokości 225 mm. W symulacjach numerycznych założono trzy warianty warunku brzegowego wymiany ciepła. W pierwszym wariancie współczynnik wymiany ciepła w każdej strefie chłodzenia zależał od temperatury powierzchni i gęstość strumienia wody bez uwzględnienia istnienia rolek. Drugi model warunku brzegowego definiował współczynnik wymiany ciepła wokół każdej dyszy natryskowej również bez uwzględnienia wymiany ciepła z rolkami. Ostatnim wariantem obliczeń był model, w którym uwzględniono lokalny współczynnik wymiany ciepła wynikający z zastosowanego układu chłodzenia oraz kontaktu z rolkami podtrzymującymi i ciągnącymi. Analizie poddano pole temperatury otrzymane w wyniku obliczeń dla trzech przyjętych wariantów warunków brzegowych. Warunek brzegowy, który uwzględnia ułożenie dysz oraz rolek pozwolił uzyskać bardziej nierównomierne, bliższe rzeczywistemu pole temperatury. Zastosowanie modelu najbardziej rozbudowanego pozwala z dużą dokładnością wyznaczyć pole temperatury na powierzchni krzepnącego pasma w maszynie COS.

EN

The calculations of ingot temperature field, which was made for carbon steel slabs were presented. The dimension of the ingot was 1500 mm wide and 225 mm high. In the numerical simulations, three models of the boundary condition of the heat transfer were used. In the first one, the heat transfer coefficient in the secondary cooling zones was calculated as a function of surface temperature and water jet density. In the second model the heat transfer coefficient is defined around each spray nozzle. In the first and second model contact with the rolls was neglected. The last variant of the calculations has been done for local heat transfer coefficient (model 2) and the contact with rolls was included. The simu-lation results for three models have been analysed. Model with the boundary condition, which takes into account the position of nozzles and rolls, has given the most accurate results of temperature fields in the continuous casting process. The calculations have been performed using self-developed software which uses the inverse method and FEM.

10

Wear-Fatigue Study of Carbon Steels

Hejwowski Tadeusz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2021

|

Vol. 15, no 3

179--190

EN

The process of conjoined stress cycling and abrasive or erosive wear is encountered in industry. However, very scant attention has been paid till now to this issue. The paper presents two test rigs designed and built to cope with this experimental problem. Tests were carried out on the range of pure iron (Armco), carbon steels namely S235JR, C45, C70U, C80U, C110U and unalloyed cast steels (L40III, L45III and L50III). Tested iron-based alloys differ in chemical composition, microstructure and Brinell hardness ranging from 80HB to 350HB. Stress cycling caused strain hardening of ferrite in hypoeutectoid steels and thus reduced their abrasive wear loss. In the hypereutectoid steel stress cycling impaired integrity of the microstructure thus increasing abrasive wear loss. Alternating stresses enhanced ploughing and cutting micromechanisms of erosion. Tensile stress in the tested cast steel had a stronger effect on wear loss than the prior stress history.

11

Electrochemical and Quantum Chemical Investigation on Adsorption of Nifedipine as Corrosion Inhibitor at API 5L X-52 Steel / HCl Acid Interface

Ikpi M. E., Abeng F. E.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

125--131

EN

Nifedipine, a pyridine derivative was investigated as corrosion inhibitor for API 5L X-52 steel in 2 M HCl solution by potentiodynamic polarization, electrochemical impedance spectroscopy and quantum chemical calculations. Statistical tools were used to compare results of the experimental methods. The results showed that nifedipine is capable of inhibiting the corrosion of API 5L X-52 steel in 2 M HCl solution. Potentiodynamic polarization results reveal that nifedipine functions as a mixed-type inhibitor and presents an inhibition efficiency of about 78% at 500 ppm. Impedance data reveal an increasing charge transfer resistance with increasing inhibitor concentration and also shows comparable inhibition efficiency of about 89-94% at 500 ppm. Thermodynamic parameters imply that nifedipine is adsorbed on the steel surface by a physiochemical process and obeys Langmuir adsorption isotherm. The calculated molecular properties namely the highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy, chemical hardness, energy gap, dipole moment, electronegativity and global nucleophilicity index all show a positive relationship to the observed corrosion inhibition efficiency.

12

Corrosion Inhibition of API 5L X52 Carbon Steel by 1-Ethyl-3-methylimidazolium-methanesulphonate and 1-Ethyl-3-methylimidazolium Acetate Ionic Liquids in Hydrochloric Acid

Ikpi Magdalene Edet, Obono Okama Ebri

Archives of Metallurgy and Materials

|

2020

|

Vol. 65, iss. 1

295--304

EN

The corrosion inhibition behaviour of 1-Ethyl-3-methylimidazolium-methanesulphonate (EMIM[MS]) and 1-Ethyl-3-methylimidazolium acetate (EMIM[Ac]) on API 5LX-52 carbon steel in 2 M HCl was investigated using weight loss, potentiodynamic polarization and electrochemical impedance methods. The corrosion rates of carbon steel decreased in the presence of these ionic liquids. The inhibition efficiencies of the compounds increased with concentration and showed a marginal decrease with a 10°C increase in temperature. Polarization studies showed the compounds to be mixed type inhibitors with stronger anodic character. The adsorption mechanism of both compounds on the metal surface was via physical adsorption and the process obeyed the El-Awardy kinetic-thermodynamic model. The associated activation energy of corrosion and other thermodynamic parameters were calculated to elaborate on the thermodynamics and mechanism of the corrosion inhibition process. EMIM[MS] was found to inhibit the corrosion of carbon steel better than EMIM[Ac] and is attributed to the presence of the highly electronegative sulphur atom in its structure and its larger molecular size.

13

Insights into factors of damage of surface rolling of railway wheels during operation

Aaskerov Hangardas, Vakulenko Igor, Grischenko Nikolaji

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2019

|

z. 105

27--33

EN

The systematization results of microstructure studies of carbon steel has made it possible to explain the mechanism of formation of certain damages to the rolling surface of railway wheels during operation. The evaluation ability of metal to strain hardening was used to explain the nature of the influence compactly located non-deformable dispersed particles on the strength properties steel during cold plastic deformation. In the process of the interaction of a railway wheel with a rail, successively occurring heterogeneities in the distribution of the plastic flow metal are one of the main reasons for the formation of defects on the rolling surface of the wheel.

14

Laser forming of steel tubes

Radek Norbert, Kurp Piotr, Pietraszek Jacek

Technical Transactions

|

2019

|

Vol. 116, iss. 1

223--229

EN

The paper presents a study on microstructure and microhardness changes obtained in the spun carbon steel tube after shaping by a laser beam. The surface of a pipe was machined circumferentially using a 1500 W CO2 laser beam at various diameters (distance from the focus). As a result, plastic deformations such as convex and narrowing shape changes were observed. The conducted research, including microhardness measurements, shows that, in comparison to the unprocessed material, the microstructure was significantly changed, both in the convex and narrowed layer.

PL

W pracy przedstawiono badania zmian mikrostruktury i mikrotwardości warstwy wierzchniej wyoblonej i przewężonej rury ze stali węglowej po laserowym kształtowaniu. Powierzchnia rury była skanowana po obwodzie wiązką lasera CO2 o mocy 1500 W przy różnych średnicach (odległościach od ogniska). W efekcie uzyskano odkształcenia plastyczne, takie jak wyoblenie i przewężenie rury. Przeprowadzone badania, w tym pomiary mikrotwardości, wykazują, że mikrostruktura uległa istotnej zmianie w stosunku do materiału rodzimego, zarówno w warstwie wyoblonej, jak i przewężonej.

15

Gazy osłonowe do spawania łukowego drutem litym (MAG) stali węglowych i niskostopowych

Niagaj Jerzy

Stal, Metale & Nowe Technologie

|

2019

|

nr 9-10

88--92

PL

Omówiono rodzaj i skład gazów używanych podczas spawania stali niestopowych i niskostopowych metodą MAG (GMAW), jak również opisano wpływ poszczególnych gazów na proces spawania i jakość złączy spawanych.

EN

The type and composition of gases used in the MAG (GMAW) welding of carbon and low-alloy steels are discussed, as well as the influence of particular shielding gases on the welding process and quality of welded joints is described.

16

Badania właściwości mechanicznych i mikrostruktury eksperymentalnych blach warstwowych walcowanych na gorąco

Walnik Bartłomiej, Woźniak Dariusz, Adamczyk Mariusz

Hutnik, Wiadomości Hutnicze

|

2019

|

Vol. 86, nr 10

309--314

PL

W artykule przedstawiono wyniki prób walcowania na gorąco blach warstwowych w linii do badań w skali półprzemysłowej (LPS), z zastosowaniem jednego przepustu z gniotem względnym około 40%. Próby technologiczne wykonano na blachach warstwowych, będących połączeniami stali: S235JR, S355J2, 42CrMo4 i X5CrNi18-10. Wykonano próby wytrzymałościowe na zginanie i ścinanie z uzyskanych połączeń. Badania mikrostruktury przeprowadzono przy użyciu mikroskopu świetlnego. Wyniki pracy wskazują na możliwość wytworzenia unikatowych wyrobów łączących w sobie cechy stali z gatunków S235JR, S355J2, 42CrMo4 i X5CrNi18-10 bezpośrednio w procesie walcowania na gorąco.

EN

The article presents the results of experiments of one pass rolling of layered sheets with relative reduction ~40%. The experiments were carried out in the semi industrial line to simulation of hot rolling process (LPS)on layered plates from steels: S235JR, S355J2, 42CrMo4 and X5CrNi18-10. Bending and shearing strength tests were carried out. Microstructure investigation was carried out with the use of a light microscope. The results of the work indicate the possibility of creating unique products composed of different types of steels: S235JR, S355J2, 42CrMo4 and X5CrNi18-10 in hot rolling process.

17

Assessing the condition of the material of pressure vessel after their long-lasting operation in the petrochemical industry using non-destructive acoustic methods and structural stress field analysis

Lyasota Igor, Sarniak Łukasz, Kustra Piotr

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2019

|

Vol. 63, No. 3

53--60

EN

The article discusses complex tests of an actual pressure vessel after its long-lasting operation in a petroleum distillation system. As a result of exposure to extreme conditions, the structural material of the vessel degraded and corroded significantly. The corrosion damage was identified and imaged using a Phased Array technique-based ultrasonic method. The subsequent stage of investigation involved hydraulic tests and the recording of acoustic emission signals. Stress concentration fields in damaged areas were identified using the FEM-based simulation method. The test results will be used to develop the complex methodology enabling the evaluation of the technical condition of pressure vessels used in the petrochemical industry. The above-named objective constitutes the primary goal of Programme LEADER VII, funded by the National Centre for Research and Development.

PL

Wykonano kompleksowe badania stanowiskowe rzeczywistego zbiornika ciśnieniowego poddanego wieloletniej eksploatacji w instalacji destylacji ropy naftowej. Na skutek pracy w warunkach ekstremalnych materiał elementów konstrukcji urządzenia uległ degradacji oraz zawierał liczne uszkodzenia korozyjne, które zostały zidentyfikowane i odwzorowane za pomocą szczegółowych badań metodą ultradźwiękową z wykorzystaniem techniki Phased Array. Na dalszym etapie badań wykonano próby hydrauliczne z rejestracją sygnałów emisji akustycznej. W celu określenia stref o koncentracji pola naprężeń w obszarach uszkodzeń dodatkowo wykonano symulację metodą elementów skończonych. Wyniki wykonanych badań stanowią bazę do opracowania złożonej metodyki oceny stanu technicznego urządzeń ciśnieniowych przemysłu rafineryjnego – głównego celu projektu badawczego Programu LIDER VII sfinansowanego przez Narodowe Centrum Badań i Rozwoju.

18

Identification of the tensile damage of degraded carbon steel and ferritic alloy-steel by acoustic emission with in situ microscopic investigations

Lyasota Igor, Kozub Barbara, Gawlik Józef

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 1

274--285

EN

The paper presents results obtained from the destructive laboratory investigation conducted on materials from pressure vessels after long-term operation in the refinery industry. Tested materials contained structural defects, which arose from improper heat treatment during steel plate manufacturing. Detailed metallographic and chemical composition tests and static tensile tests were conducted. Next, complex tensile tests were conducted with simultaneous acoustic emission (AE) monitoring while observing microstructural changes by light microscopy. From the laboratory tests, the correlations between the AE signal parameters and material microstructural damage during the tensile tests were developed. The results will be used as a basis of new algorithms for the structural condition assessment of in-service pressure equipment.

19

Structure and properties of the steel railway wheel disc after forced cooling

Vakulenko I., Grischenko N., Vakulenko L., Efremenko V., Proiydak S., Perkov O.

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2018

|

z. 98

173--180

EN

The technological use of accelerated cooling makes it possible to improve the carbon steel properties of the all-rolled railway wheel disc. The properties’ complex depends on the temperature of the accelerated cooling termination. This is determined by the ratio of the carbon atoms emitted from the supersaturated solid solution to the crystal structure defects and dispersion strengthening from carbide phase particles. If the cooling stops at a temperature above 350°C, the decline rate of the strength properties increases. This is caused by the excessive softening effect of the solid solution breakdown and cementite spheroidization during the processes of dispersion hardening.

20

Model wymiany ciepła w procesie ciągłego odlewania stali z uwzględnieniem lokalnego warunku brzegowego

Rywotycki M., Hadała B., Malinowski Z.

Przegląd Mechaniczny

|

2018

|

nr 3

40--43

PL

W pracy przedstawiono obliczenia symulacyjne pola temperatury wykonane dla wlewka płaskiego ze stali węglowej. Modelowano proces ciągłego odlewania pasma o szerokości 1500 mm i wysokości 225 mm. W symulacjach numerycznych założono trzy warianty warunku brzegowego wymiany ciepła. W pierwszym wariancie współczynnik wymiany ciepła w każdej strefie chłodzenia zależał od temperatury powierzchni i gęstości strumienia wody bez uwzględnienia istnienia rolek. Drugi model warunku brzegowego definiował współczynnik wymiany ciepła wokół każdej dyszy natryskowej również bez uwzględnienia wymiany ciepła z rolkami. Ostatnim wariantem obliczeń był model, w którym uwzględniono lokalny współczynnik wymiany ciepła wynikający z zastosowanego układu chłodzenia oraz kontaktu z rolkami podtrzymującymi i ciągnącymi. Analizie poddano pole temperatury otrzymane w wyniku obliczeń dla trzech przyjętych wariantów warunków brzegowych. Warunek brzegowy, który uwzględnia ułożenie dysz oraz rolek, pozwolił uzyskać bardziej nierównomierne, bliższe rzeczywistemu pole temperatury.

EN

The calculations of ingot temperature field, which was made for carbon steel slabs were presented. The dimension of the ingot was 1500 mm wide and 225 mm high. In the numerical simulations, three models of the boundary condition of the heat transfer were used. In the first one, the heat transfer coefficient in the secondary cooling zones was calculated as a function of surface temperature and water jet density. In the second model the heat transfer coefficient is defined around each spray nozzle. In the first and second model contact with the rolls was neglected. The last variant of the calculations has been done for local heat transfer coefficient (model 2) and the contact with rolls was included. The simulation results for three models have been analysed. Model with the boundary condition, which takes into account the position of nozzles and rolls, has given the most accurate results of temperature fields in the continuous casting process.