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1

Attempts to Modify Austenitic Steel with Carbon Nanotubes

Górka Jacek, Kik Tomasz, Burda Michal

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

349--356

EN

In this work, research on influence of multiwalled carbon nanotubes (MWCNTs), produced in Catalic Chemical Carbon Vapor Deposition, NANOCYLTM NC7000CNTs on a structure and properties of AISI 301 steel remelted by TIG arc. In the assessment of influence a type of carbon on properties and structure of austenitic steel, as a carbon filler was use also carburizer. In the specimens (AISI 301 plates) with dimensions 155×60×7 [mm] were drilled holes with 1.3 mm diameter and placed 0.5 mm under specimen surface. Next, to the drilled holes was implemented CNTs, carburizer and mixture of these both powders. Prepared specimens were remelted by TIG method on the CASTOTIG 2200 power source with 2.4 mm tungsten thoriated electrode with parameters sets for obtain 3.0 mm penetration depth. Remelted specimens were cut into the half of the welds distance and prepared for metallographic examinations. Cross sections of the specimens were tested on classical metallography microscopes, hardness tests, SEM analyses (on JEOL 5800 LV SEM EDX equipment) and phase identification by X-ray phase analysis on Philips APD X’Pert PW 3020 diffractometer. Hardness analysis indicates about 25% increase of hardness in the remelted area when the CTNs are used. In the specimens with carburizer there is no significant changes. SEM analyses of remelted areas on AISI 301 specimens modificated with CNTs, indicates that dark areas, initially interpret as one of the phase (based on optical microscope) is finally densely packed bladders with dimensions from 50 nm up to a few µm. These bladders are not present in the specimens with carburizer filler. High resolution scanning microscopy allow to observe in the this area protruding, longitudinal particles with 100-300 nm length. For identification of this phase, X-ray analysis was done. But very small dimensions of used CNTs (diameters about 9,5 nm), random orientation and small weight amount can make difficult or impossible to CNTs detection during XRD tests. It means that it is not possible to clearly determine nature of particles filling the cavities, it is only possible to suppose that they are CNTs beams with nanoparticles comes from their disintegration. Results of the researches indicates, that fill in the weld pool with different form of carbon (CNTs and carburizer) it is possible to achieve remelted beads with different structure and hardness distribution. It confirms validity of the research continuation with CNTs as a modifier of steels and also other metals and theirs alloys.

2

Examination of Electrical Resistance of Carburizers Used for Cast Iron Production

Książek D., Koza M., Bieroński M., Krasa O., Kuś R.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

65--68

EN

The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers. The measurements were performed according to the authors’ own method based on recording the electric current flow through the compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ. The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in tabular and, additionally, in graphic form.

3

Zmniejszanie emisji CO2 w procesie elektrostalowniczym poprzez stosowanie alternatywnych materiałów nawęglających we wsadzie

Zdonek B., Szypuła I.

Prace Instytutu Metalurgii Żelaza

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2010

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T. 62, nr 1

207-212

PL

Przy wytwarzaniu stali w piecu łukowym emituje się do otoczenia od 71,9 do 77,4 kg CO2 na tonę ciekłej stali. Wskaźnik emisji CO2 przy wytwarzaniu energii elektrycznej opartym na węglu wynosi w Polsce około 652 g/kWh, czyli wytwarzanie jednej tony stali powoduje emisję CO2 wynoszącą w zależności od jednostkowego zużycia energii elektrycznej (od 405 - 475 kWh/Mg stali) od 264 do 310 kg. Zwiększenie uzysku węgla wprowadzanego do wsadu w postaci nawęglaczy poprzez stosowanie ich w jak najlepszej postaci fizycznej wpływa na zmniejszenie jednostkowego zużycia węgla o 1,5 kg/Mg stali co odpowiada ograniczeniu emisji CO2 o 5,5 kg/Mg stali. W publikacji przedstawiono zagraniczne i własne doświadczenia dotyczące badań nad zastosowaniem we wsadzie do pieca łukowego jako alternatywnych środków nawęglających rozdrobnionych opon oraz kompozytu węglowo (gumowo) - stalowego. Zamiana węgla na kompozyt we wsadzie może przynieść efekt ekonomiczny 1,2 zł/Mg stali i efekty niewymierne w postaci dodatkowego żelaza z kordu i energii chemicznej ze spalania pierwiastków wchodzących w skład gumy.

EN

During EAF process is emitted to the environment 71.9 to 77.4 kg CO2 / Mg of liquid steel. CO2 emission rate in coal based electric power production in Poland amounts about 652 g / kWh, what means that production one ton of steel results in CO2 emission amounting in dependence on electric power rate ( 405 to 475 kWh / Mg of steel) from 264 to 310 kg. Increased carbon rate assimilation of these carburisers, introduced into charge in the best possible physical form and in the best possible way, results in decrease coal specific consumption by 1.5 kg / Mg of liquid steel, what corresponds with CO 2 emission reduction by 5.5 kg / Mg of liquid steel. The foreign and own experiences and research into the use of ground tyres and carbon(rubber)-steel composite in arc-furnace charge as the alternative carburising agents is presented herein. The exchange of coal for composite to be used in charge may bring the economic effect ofPLN 1.21 Mg of steel and immeasurable effects in the form of extra iron from the cord and chemical energy from combustion of the elements contained in rubber.

4

The carburizer influence on the crystallization process and the microstructure of synthetic cast iron

Janerka K., Bartocha D., Szajnar J., Jezierski J.

Archives of Metallurgy and Materials

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2010

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Vol. 55, iss. 3

851-859

EN

The problems of synthetic cast iron production on the steel scrap and various carburizers (natural and synthetic graphite, petroleum coke, anthracite, cupola coke and charcoal) basis were presented in the paper. Until now the authors in their papers had analyzed mainly carbon assimilation by the liquid metal rate (recarburization efficiency) when these carburizers and various methods of recarburization were used [1,2,3,4]. The analysis covered the chemical composition and the properties of carburizers commonly used in foundries [5,6] and mechanical properties of the cast iron obtained on the steel scrap basis, too [2,7,8,9]. The computer modeling of heating and dissolution of carburizers’ particles inside liquid metal were carried out, too [10,11]. The crystallization process of the synthetic cast iron analysis and that produced on pig iron basis for comparison were presented. There was observed that the carburizers change the DTA (Derivative Thermal Analysis) curves in specific temperature ranges. The authors presented some experimental results in form of recorded DTA curves. The presented results show also carburizers microstructures and synthetic cast iron and made on pig iron basis structures, too. The problems given under consideration in the paper has a purpose of set up a discussion on "heredity of cast iron" – some charging materials properties transferred to cast iron. Does such an issue exist and if yes, in what extent it decides of melted alloys properties (synthetic cast iron in described example)?

PL

W artykule przedstawiono zagadnienia związane z wytwarzaniem żeliwa syntetycznego na bazie złomu stalowego i różnych rodzajów materiałów nawęglających (grafitu naturalnego i syntetycznego, koksu naftowego, antracytu, koksu odlewniczego i wegla drzewnego). Dotychczas autorzy w swoich publikacjach analizowali przede wszystkim stopień przyswojenia węgla przez ciekły metal (efektywnosc nawęglania) przy stosowaniu tych nawęglaczy i różnych metod nawęglania [1,2,3,4]. Analiza obejmowała również skład chemiczny i właśnosci najczęściej stosowanych w odlewnictwie nawęglaczy [5,6] oraz własności mechaniczne żeliwa wytopionego na bazie złomu stalowego [2,7,8,9]. Prowadzone są równiez symulacje komputerowe procesu nagrzewania i rozpuszczania cząstek nawęglaczy znajdujących się w ciekłym metalu [10,11]. W artykule przedstawiono analizę procesu krzepnięcia żeliwa syntetycznego i dla porównania żeliwa uzyskanego na bazie surówki. Zauważono, że materiały nawęglajace zmieniają przebieg krzywych Analizy Termiczno Derywacyjnej w pewnych zakresach temperatury. Autorzy przedstawili część uzyskanych wyników pomiarów w postaci zarejestrowanych krzywych ATD. Zaprezentowany materiał obejmuje również struktury materiałów nawęglających i struktury żeliwa syntetycznego oraz wytopionego na bazie surówki. Podjęta w artykule tematyka ma na celu wywołanie dyskusji o "dziedzicznosci" cech materiałów wsadowych przenoszonych do żeliwa. Czy takie zagadnienie istnieje i w jakim stopniu decyduje o własnościach wytopionych materiałów (w analizowanym przypadku żeliwa syntetycznego)?

5

Czynniki wpływające na parametry procesu pneumatycznego nawęglania

Janerka K.

Archiwum Odlewnictwa

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2005

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R. 5, nr 15

170--181

PL

W artykule przedstawiono wyniki badań siły naporu dynamicznego strumienia dwufazowego na powierzchnię ośrodka ciekłego. Przedstawione badania nie dotyczyły właściwego procesu wdmuchiwania (do ciekłego metalu) były, bowiem badaniami mającymi określić jedynie wielkość oddziaływania strumienia po opuszczeniu lancy wdmuchującej. Pozwoliły one określić zasadniczy przedział zmienności wartości siły naporu oraz podstawowe parametry wpływające na jej wartość.

EN

In the article has been presented the results of the experiments with diphase stream force on the liquid medium surface. The experiments were the first one for making descriptions of stream effect influence after outgoing the lance outlet. It has made possible to know the main value of stream force and the parameters which effect on it. On the powder injection process have influenced many parameters connected with diphase stream dynamics introduced into liquid alloy. It is very important with use of the electric crucible furnace where it is necessary to use non-immersed lance. But it may cause the small stream range in liquid. That is the reason to know every phenomenon connected with introducing of diphase stream through air-liquid alloy surface. The experiments are the part of bigger one to explain and describing those phenomenons.