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Thermodynamic Analysis of Precipitation Process of Complex Carbonitride TixV1-xCyN1-y in HSLA-Type Steel

Wojtacha Anna, Opiela Marek

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 4

64--73

EN

The paper presents a detailed analysis of the MX-type interstitial phase precipitation process and a thermodynamic analysis of the TixV1-xCyN1-y carbonitride precipitation in austenite. The subject of research analysis was the newly developed HSLA-type steel containing 0.175% C, 1.02% Si, 1.87% Mn, 0.0064% N, 0.22% Mo, and microadditions 0.022% V and 0.031% Ti. Analysis of the process of precipitation of MX interstitial phases under thermodynamic equilibrium conditions proved that the first phase that precipitates in the austenite of the tested steel is TiN-type nitride. The onset temperature of this phase was 1450°C. Subsequently, carbides of the TiC-type, VN-type nitrides and VC-type carbides, for which the precipitation onset temperatures were 1180°C, 870°C and 775°C will be released, respectively. The analysis of the precipitation process of the complex carbonitride in austenite under thermodynamic equilibrium conditions was based on the Hillert and Staffansson model, developed by Adrian, with the use of the CarbNit computer program. The beginning of carbonitride precipitation with the stoichiometric composition Ti0.985V0.015C0.073N0.927 occurred at the temperature of 1394°C. At 850°C practically all of the Ti is bound in the carbonitride of the stoichiometric composition Ti0.883V0.117C0.378N0.622. At the same temperature, a significant part of microaddition V will be dissolved in austenite, which means that vanadium will have a lesser effect on the formation of a fine-grained austenite structure, but more strongly on the precipitation hardening of steel by the dispersion VN and V particles (C,N) released during the cooling of the products.

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Correlation between spatial distribution of the components of reactive plasma flow and the stoichiometry and defectiveness of deposited coatings

Walkowicz J., Smolik J., Brudnias R., Kułakowska-Pawlak B., Żyrnicki W.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

712-718

EN

Purpose: The subject of the presented research was reactive plasma generated by circular vacuum-arc sources used for deposition of thin hard coatings. Design/methodology/approach: Experimental investigations on spatial distribution of ionized and excited plasma components were performed with the use of the optical emission spectroscopy. Quantitative analysis of microdroplets distribution was carried out using measuring optical microscope supplied with the numerical image analysis system. Findings: Based on the obtained radial distributions of volatile and condensed components the general picture of plasma flow emitted by a single circular arc source was reconstructed. Radial distributions of analysed emitting elements and analysed fractions of microdroplets showed layered structures that depended on the discharge conditions. Research limitations/implications: The spectral method used for the reconstruction of concentration distributions of ionised and excited plasma components generated by a single circular arc source could not be used for reconstruction of such distributions in the vacuum chamber of the industrial device. Originality/value: The carried out investigations showed that the differences in spatial distributions of plasma active elements determine the uniformity of crystallization conditions in vacuum-arc deposition processes performed in large-scale multi-source industrial devices.

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Nadmiarowe fazy w wysokoazotowych stalach austenitycznych

Kaputkina L., Svjażin A., Siwka J., Prokoszkina W.

Hutnik, Wiadomości Hutnicze

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2007

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Vol. 74, nr 7

357-363

PL

Badano zmiany zawartości azotu w austenicie po nagrzewaniu próbek do różnych temperatur i ich wygrzewaniu w różnych czasach. Ustalono, że w warunkach typowego nagrzewania w celu przesycenia bazowej stali Crl8Nil0Ti w jej strukturze występują nie rozpuszczone w roztworze starym azotki, których ilość zwiększa się ze wzrostem zawartości azotu w stali. Jest możliwe prawie całkowite rozpuszczenie się azotków przez nagrzanie metalu do temperatury 1200 °C i wygrzewanie go przez czas dłuższy niż 30 min. Zawartość azotu w austenitycznych stalach wysokoazotowych powinna być zbilansowana z zawartością innych pierwiastków stopowych w zależności od pożądanej struktury: austenit lub austenit i fazy nadmiarowe.

EN

Variations in the nitrogen content of austenite after heating the specimens up to different temperatures and then soaking them for different periods of time were investigated. It has been found that, under the conditions of typical heating to supersaturate the base Cr18Ni10Ti steel, nitrides undissolved in the solid solution occur in its structure, the amount of which increases with increasing nitrogen content of steel. Almost complete dissolution of nitrides is possible by heating the metal up to a temperature of 1200 °C and then soaking it for a period of time not longer than 30 min. The nitrogen content of high-nitrogen austenitic steels should be balanced with the contents of other alloy-forming elements, depending on the desired structure: austenite or austenite and excess phases.

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Thermodynamic analysis of the kinetics of carbonitride precipitation in HSLA steels.

Adrian H.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

171-178

EN

Precipitation of carbonitride in HSLA steel containing up to three microalloying elements was analysed, using classical theory of diffusion controlled nucleation. For this purpose the driving force for carbonitride nucleation is calculated using a thermodynamic model. The results of calculation show, that the critical nucleus formed at high temperature is richer in N and element having the highest chemical affinity for N compare to the bulk precipitate at equilibrium. On the basis of analysis a kinetic model was developed for predicting start times, for precipitation of carbonitride in austenite.

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Analysis of the properties of carbonitrides in HSLA steels.

Osuch W., Adrian H.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

303-306

EN

The results of complex analysis of the size of (Ti, Nb, V) (C, N) carbonitride particles are presented. The morphology of particles, their size distributions and chemical composition were investigated. The results of investigations were compared with calculated data obtained using the thermodynamic model for carbonitrides precipitation in HSLA steels.