Wyniki wyszukiwania - BazTech

1

The influence of nonmetallic inclusion on strain hardening carbon steel

Vakulenko Igor, Vakulenko Leonid, Proydak Svetlana

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2019

|

z. 103

193--198

EN

On a fragment of the rim of a railway wheel removed from service, the volume of the metal with non-metallic inclusions located near the tread surface was investigated. The use of the microhardness measurement technique made it possible to establish the nature of strain hardening of carbon steel near non-metallic inclusions. It showed that with a normal orientation of the plastic flow relative to the inclusion surface, the metal volumes undergo hardening. In proportion to the appearance of a fraction of the tangential component of the deformation near the nonmetallic inclusion, a decrease in the degree of hardening of the metal was observed.

2

The Influence of Adsorbed Al2O3 Inclusions on the Viscosity Behavior of Mould Slag

Kalisz D., Kuglin K.

Archives of Foundry Engineering

|

2019

|

iss. 2

67--74

EN

The role of slag in the process of continuous casting of steel (CCS) is reduced to the thermal and chemical insulation of the liquid steel surface, and additionally to refining. The ability to adsorb non-metallic inclusions flowing off from the crystallizer, mainly Al2O3, determines its physicochemical properties. As a result of adsorption and dissolution of inclusions tin he liquid layer the viscosity and thickness of mould flux change, which eventually affects the technological parameters and behavior of slag in the crystallizer. The influence of aluminum oxide on the viscosity of slag was empirically investigated with a structural viscosity model worked out by Nakamoto. The results of the simulation are presented in the form of plots. Authors observed a significant influence of Al2O3 on the slag viscosity, which suggests that this effect should be taken into account when selecting chemical composition of mould flux for definite types of steel. The results of calculations also show that the disturbances in casting caused by the use of the mould slag may be connected with the content of non-metallic inclusions in steel.

3

Interaction mechanism of non-metallic particles with crystallization front

Żak P. L., Kalisz D., Rączkowski G.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 1

205--210

EN

The process of steel solidification in the CCS mould is accompanied by a number of phenomena relating to the formation of non-metallic phase, as well as the mechanism of its interaction with the existing precipitations and the advancing crystallization front. In the solidification process the non-metallic inclusions may be absorbed or repelled by the moving front. As a result a specific distribution of non-metallic inclusions is obtained in the solidified ingot, and their distribution is a consequence of these processes. The interaction of a non-metallic inclusion with the solidification front was analyzed for alumina, for different values of the particle radius. The simulation was performed with the use of own computer program. Each time a balance of forces acting on a particle in its specific position was calculated. On this basis the change of position of alumina particle in relation to the front was defined for a specific radius and original location of the particle with respect to the front.

4

Microstructure Examinations in Corners of the Low-Carbon Steel Slabs from Continuos Caster Machine

Kwinta G., Kara S., Kalandyk B., Zapała R., Pałka P.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 4

2051--2056

EN

The exposed selvedge layers in slabs cast by the continuous process should be free from surface defects, which in most cases appear in the form of cracks on the casting surface and run to its interior. In addition to the parameters of the casting process, the occurrence of such defects depends on the chemical composition of cast steel, on the segregation of surface active elements and formation of the precipitates of carbides, nitrides and other phases. Due to the frequent occurrence of defects in corners of the slabs, non-destructive testing was performed on the mechanically cleaned surfaces of slabs. The test material was low-carbon API(American Petroleum Institute API 5L standard) steel micro alloyed with Nb and Ti designed for the production of pipes to handle gas, oil and other liquid and gaseous fuels. Despite the use of different methods of inspection, i.e. ultrasonic, magnetic particle and penetrant, cracks were not traced in the examined material. Then, from the corners of the examined slabs, specimens were cut out for metallographic examinations. The main purpose of these examinations was to disclose the presence of possible cracks and micro cracks on the surfaces transversal and longitudinal to the direction of casting. At the same time, studies were conducted to establish the number and morphology of non-metallic inclusions in selvedge layers of the slab corners and axis. Additionally, hardness of the slabs was measured. The conducted studies revealed only some minor differences in the slab hardness along its axis (130 ÷ 135 HB) and in selvedge layers (120 ÷ 123 HB).

5

Analysis of Agglomeration of Al2O3 Particles in Liquid Steel

Kalisz D., Żak P. L., Kuglin K.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 4

2091--2096

EN

The removal of non-metallic inclusions from liquid steel is a result of co-operation of fluctuation, adhesion and agglomeration effects, with emphasis on agglomeration which plays the most important role. It is based on a few types of collisions between non-metallic particles, where turbulent collisions are most prominent. As a result of agglomeration, nonmetallic inclusions are intensely removed through flotation and increase of different dimensions of inclusions, which manifests itself with the occurrence of clusters mainly composed of Al2O3 precipitations. Authors investigated the agglomeration effect by making computer simulations with the use of the PSG method. The calculations were performed for a definite population of spherical particles of radius r in the steel volume. The applied calculation method allows for analyzing the dynamics of the collision process. The assumed initial number of particles remains constant, only the number of particles in specific size-groups varies. It was also revealed that the process of agglomerates formation is much faster for particles having a bigger initial radius. In the case of very small precipitations (r=1 μm) their removal through agglomeration is very difficult because the probability those collisions can take place between them rapidly decreases.

6

Effect of chemical composition and plastic deformation on corrosion properties of highMn austenitic steels in alkaline solution

Kozłowska A., Grajcar A

Archives of Materials Science and Engineering

|

2016

|

Vol. 77, nr 1

31--39

EN

Purpose: The aim of the paper is to compare the corrosion properties of two high-Mn austenitic steels with various Al and Si additions in 0.1M NaOH solution using a potentiodynamic method. Design/methodology/approach: The steels used for the investigation were thermomechanically rolled in 3 passes. The final thickness of about 2 mm was obtained at a temperature of 850°C. Three groups of samples were prepared: thermomechanically rolled, thermomechanically rolled and additionally annealed at 900°C for 20 min, thermomechanically rolled and additionally cold deformed in static tensile test to total elongation of 36%. Corrosion resistance of investigated steels was examined using the potentiodynamic method. The metallographic inspection of corrosion damage included scanning electron microscope observations. The chemical analyses of the corrosion pits were carried out using EDS techniques. Findings: It was found that X4MnSiAlNbTi27-4-2 and X6MnSiAlNbTi26-3-3 steels were characterized by relatively high corrosion resistance in 0.1M NaOH solution independently of their state. EDS analysis revealed that corrosion pits nucleated preferentially at nonmetallic inclusions such as MnS and AlN. Results of potentiodynamic tests showed that cold deformation had the highest influence on decreasing the corrosion resistance of investigated steels. Thermomechanically treated and supersaturated specimens showed lower values of corrosion current density and consequently less amount of corrosion damage. Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese austenitic steels, the impedance spectroscopy investigations will be carried out. Practical implications: The knowledge of the corrosion resistance of high-Mn steels has a significant effect on their industrial application in the automotive industry. Originality/value: The corrosion resistance of two high-manganese austenitic steels with different initial microstructures was compared in alkaline solution.

7

Technologia produkcji wielkogabarytowych odlewów staliwnych przeznaczonych do zastosowań w ekstremalnych warunkach eksploatacji

Żak A., Zdonek B., Adamczyk M., Szypuła I., Kutera W., Kostrzewa K.

Prace Instytutu Metalurgii Żelaza

|

2015

|

T. 67, nr 2

21--28

PL

Rosnący popyt na odlewy staliwne przeznaczone do zastosowań w temperaturach do minus 40oC skłonił Odlewnię Pioma Sp. z o.o. do podjęcia próby produkcji takich odlewów w oparciu o niskonakładową modyfi kację technologii wytapiania, odlewania oraz obróbki cieplnej odlewów. W pracy na podstawie wyników badań odlewów wytwarzanych ze staliwa w gatunku G18NiMoCr3-6 według stosowanej obecnie technologii, opracowano wytyczne do modyfi kacji technologii w zakresie zmiany składu chemicznego staliwa, sposobu wytapiania staliwa i obróbki cieplnej odlewów. Główne zmiany obejmowały wyeliminowanie ze składu staliwa dodatku tytanu oraz podwyższenie zawartości węgla i pierwiastków stopowych, zmianę sposobu odtleniania staliwa, wprowadzenie modyfikacji wtrąceń niemetalicznych za pomocą drutu rdzeniowego Ca-Si oraz zmieniono wybrane parametry obróbki cieplnej odlewów. Wykonana seria doświadczalnych wytopów staliwa w oparciu o zmodyfikowaną technologię wykazała, że w obecnych warunkach technicznych Odlewni możliwe jest spełnienie wymagań odbiorców, co do właściwości mechanicznych odlewów o grubości do 75 mm, w szczególności udarności równej co najmniej 42 J, dla próbki KV, w temperaturze minus 40°C. W celu spełnienia wymagań odbiorców dla odlewów o większych przekrojach, w oparciu o uzyskane wyniki badań czystości staliwa i właściwości mechanicznych opracowano zalecenia do innowacyjnej technologii rafinacji pozapiecowej ciekłego staliwa.

EN

The growing demand for steel castings intended for applications at up to minus 40°C induced the Odlewnia Pioma Sp. z o.o. foundry to make an attempt to manufacture such castings based on a low-cost modification of technology for melting, casting and heat treatment of castings. In this paper, the guidelines for technology modifications with regard to the change in cast steel chemical composition, cast steel melting method and heat treatment of castings were developed based on results of investigations for castings manufactured from G18NiMoCr3-6 cast steel in accordance with the current technology. The main changes included the elimination of titanium additive from the cast steel composition and increase in the contents of carbon and alloying elements, a change in the cast steel deoxidation method, introduction of modifications to non-metallic inclusions by means of Ca-Si fl ux-cored wire, and selected casting heat treatment parameters were changed. The series of experimental cast steel melts manufactured using the modified technology have revealed that it is possible to meet the buyers’ requirements for mechanical properties of castings with thickness of up to 75 mm, in particular impact strength of at least 42 J, for KV sample at minus 40°C under the present technical conditions of the Foundry. To meet the buyers’ requirements for castings with higher cross-sections, the recommendations on innovative technology for secondary refining of liquid cast steel were developed based on obtained results of investigations of cast steel purity and mechanical properties.

8

Oddziaływanie ceru, lantanu i neodymu na morfologię i skład chemiczny wtrąceń niemetalicznych w stalach mikrostopowych

Opiela M.

Hutnik, Wiadomości Hutnicze

|

2014

|

Vol. 81, nr 3

142--148

PL

W artykule opisano modyfikację składu chemicznego wtrąceń niemetalicznych pierwiastkami ziem rzadkich w nowo opracowanych stalach mikrostopowych. Badane stale przeznaczone są do produkcji elementów kutych metodą obróbki cieplno-plastycznej. Wytopy wykonano w indukcyjnym piecu próżniowym, a modyfikację wtrąceń niemetalicznych przeprowadzono miszmetalem w ilości 2,0 g na 1 kg stali. Skład chemiczny i morfologię wtrąceń niemetalicznych modyfikowano dodatkami Ce, La i Nd. Stwierdzono, że stale cechuje duża czystość metalurgiczna związana z małym stężeniem siarki (0,004%), fosforu (od 0,006 do 0,008%) oraz tlenu (6 ppm). Dużej czystości metalurgicznej odpowiada mały udział powierzchniowy wtrąceń niemetalicznych, wynoszący około 0,077%. Zdecydowaną większość stanowią drobne, globularne wtrącenia tlenkowo-siarczkowe lub siarczkowe o średniej powierzchni przekroju 17 mm2.

EN

The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels has been discussed in the paper. The investigated steels are assigned for production of forged elements by thermo-mechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0g per 1kg of steel. The chemical composition and morphology of non-metallic inclusions was modified by additions of Ce, La and Nd. It was found that using material charge of high purity and a realization of metallurgical process in vacuum conditions result in a low concentration of sulfur (0.004%), phosphorus (from 0.006 to 0.008%) and oxygen (6 ppm). The high metallurgical purity is confirmed by a small surface fraction of non-metallic inclusions averaging 0.077%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean cross-section of 17 μm2.

9

Mathematical modelling of the tundish inertization practice

Martins Braga B., Parreiras Tavares R.

Computer Methods in Materials Science

|

2014

|

Vol. 14, No. 2

138--149

EN

The inertization practice for a 17.7 tons of steel continuous casting tundish has been studied by means of a three-dimensional non-isothermal mathematical model. The model considers a single gaseous phase composed of argon and air. Turbulence was accounted for with the standard k-ε model. The calculations were carried out using the commercial CFD software ANSYS CFX. Different configurations of the inertization system were simulated and a novel approach was utilized to discuss model findings. The results indicated that the present configuration is ineffective and new ones were suggested.

PL

W pracy omówiono modelowanie procesu wytwarzania atmosfery obojętnej w przestrzeni roboczej kadzi pośredniej ciągłego odlewania stali. Zastosowano przestrzenny model dla warunków zmiennej temperatury. Model uwzględnia fazę gazową składającą się z argonu i powietrza. Turbulencje w przepływie gazu modelowano za pomocą standardowej metody k-ε. Symulacje CFD przepływu (ang. Computational Fluid Dynamics) wykonano w komercyjnym oprogramowaniu ANSYS CFX. Rozważono różne konfiguracje procesu tworzenia atmosfery obojętnej. Analiza wyników symulacji wykazała, że obecnie stosowana konfiguracja procesu jest nieefektywna. Na podstawie przeprowadzonej analizy uzyskanych wyników zaproponowano nowe podejście do tego procesu

10

The influence of impurities in feed ingots on the quality of castings made from nickel superalloy IN-713C

Binczyk F., Cwajna J., Sozańska M., Gradoń P.

Archives of Foundry Engineering

|

2013

|

Vol. 13, iss. 4

5--8

EN

The paper presents the results of research on the impact of impurities in the feed ingots (master heat) on the precipitation of impurities in the ATD thermal analysis probe castings. This impurities occur mostly inside shrinkage cavities and in interdendritic space. Additionally, insufficient filtration of liquid alloy during pouring promotes the transfer of impurities into the casting. The technology of melting superalloys in vacuum furnace prevents the removal of slag from the surface of molten metal. Because of that, the effective method of quality assessment of feed ingots in order to evaluate the existence of impurities is needed. The effectiveness of ATD analysis in evaluation of purity of feed ingots was researched. In addition the similarities of non-metallic inclusions in feed ingots and in castings were observed.

11

Wpływ procesu odtleniania i modyfikacji na udział i morfologię wtrąceń niemetalicznych staliwa węglowego

Kalandyk B.

Archiwum Odlewnictwa

|

2006

|

R. 6, nr 18/1

419--424

PL

Zaprezentowano wyniki badań ilości, morfologii i składu chemicznego wtrąceń niemetalicznych występujących w staliwie węglowym po wprowadzeniu do kadzi Al+FeCa-Si; Al+FeCa-Si +FeV lub Al+FeTi. Badania te przeprowadzono w warunkach przemysłowych. Stwierdzono, że najniższe zawartości wtrąceń otrzymano po podwójnym odtlenianiu Al +FeCa-Si i modyfikacji FeV.

EN

Influence of double deoxidations and modification of carbon cast steels on the morphology of non-metallic inclusions were studied. It was shown that the lowest inclusion content obtained by the initial desulphurization of steels and than its deoxidation by Al+FeCa-Si and modification by FeV (0,12%).

12

Charakterystyka morfologiczna nanowtrąceń niemetalicznych powstających w przemysłowych wlewkach ciągłych o małych przekrojach

Marcisz J.

Prace Instytutu Metalurgii Żelaza

|

2004

|

T. 56, nr 2

31-33

PL

Celem pracy było ustalenie, czy w przemysłowych wlewkach ciągłych o przekrojach 100 i 120 mm występują nonowtrącenia (o wielkości poniżej 1 um). Stwierdzono, że zmniejszenie przekroju wlewka powoduje rozdrobnienie wtrąceń w zakresie średnie powyżej 1um. Wygrzewanie wlewka w temperaturze 1300 stopni Celsjusza powoduje rozpuszczenie ok. 90% wtrąceń o średnicach 100-300 nm.

EN

The purpose of this paper was to determine whether there were any nanoinclusions (below 1um) in industrial continuous casting, which cross-sections were 100 and 120 mm. It was found that the reduction in cross-section of a casting caused size reduction of inclusions with diameters above 1 um. Holding a casting at 1300 C degree causes that approx. 90% of inclusions with diameters of 100-300 nm is dissoluted.