Modeling of Oxide Precipitates Chemical Composition During Steel Deoxidization

Abstract

The work analyses the possibilities of modeling the process of steel deoxidization from the view-point of thermodynamic equilibrium between liquid steel and oxide precipitates. Two calculation procedures were employed, which make use of WYK STAL authors' program and commercial software FactSage. Two kinds of steel were taken into account, one with considerable titanium addition and the second without titanium. The variation of chemical composition of non-metallic precipitates with titanium concentration, aluminum addition and temperature was determined. The apparent influence of assumed thermodynamic model on the composition of non-metallic precipitate was stated.Keywords: simulation, deoxidization, steel, titanium, aluminum, nitrides Praca analizuje możliwości modelowania procesu odtleniania stali w aspekcie równowagi termodynamicznej między ciekłą stalą a wydzieleniami tlenkowymi. Zastosowano dwie procedury obliczeniowe z wykorzystaniem komercyjnego pakietu FACTSage oraz własnego programu WYK STAL. Obliczenia wykonano dla dwóch gatunków stali, z których jedna posiada znaczny dodatek tytanu. Obliczono, jak zmienia się skład wydzieleń tlenkowych pod wpływem stężenia tytanu, dodatku glinu oraz temperatury. Stwierdzono wyraźny wpływ przyjętego modelu termodynamicznego procesu na uzyskany skład fazy niemetalicznej.

Modeling of TiN and Ti2O3 Precipitates Formation During Solidification of Steel/ Modelowanie Powstawania Wydzieleń TiN I Ti2O3 W Procesie Krzepnięcia Stali

“…The activity of oxide phase components was established from expressions for a regular solution model. The calculation accounted for the activity parameters after Banya [1, [4][5]. The calculations were performed for the metallic/non-metallic interface equilibrium conditions with the equilibrium constants for inclusion formation reactions in liquid steel [1,7,8,11].…”

“…The activity coefficients of particular steel components were determined from Wagner-Chipman equation. The first order activity parameters were assumed from [1, [4][5]. The activity of oxide phase components was established from expressions for a regular solution model.…”

“…On the other hand, when the nitrogen content is too low and the steel contains oxygen, titanium oxides will be consequently formed. The computer simulations performed by the authors [4], [5] with the use of commercial software FactSage and own computer program WYK Stal proved that TiN is formed in the secondary refinery process which precedes casting. The microstructure of the cast steel cannot be modified with the formed TiN precipitations.…”

“…It was also observed that the finest ferrite structure can be obtained using pure titanium oxides TiO 2 and Ti 2 O 3 . However, in reality oxides usually occur in solutions which disqualifies them as structure modifiers [1], [4][5]. Titanium nitride precipitates can be formed only when liquid steel contains appropriate amounts of titanium and nitrogen.…”

PSG Method for Simulating Agglomeration of Al2O3Inclusions in Liquid Steel

“…Clusters of non-metallic particles concentrate in large sets of inclusions and have a negative impact on the properties of steel products. On the other hand, large agglomerations of large-diameter inclusions can be removed from liquid steel more easily [9][10][11][12][13][14][15][16][17][18][19][20]. Nakaoka [3] claimed that an adverse effect may take place during refining operations, i.e.…”