Formation of Non-metallic Inclusions of Si-killed Stainless Steel during GOR Refining Process

Abstract

The formation mechanism of inclusions in Si-killed 304 stainless steel was studied by industrial experiments during GOR refining process and thermodynamic calculations. A lager number of CaO-SiO2-MgO-Al2O3-MnO-CrOx liquid spherical inclusions with different size (from 1 μm to 22 μm) had been found after deoxidization of FeSi alloy in 10 minutes. The calculation result of FactSage 6.3 software assisted in confirming that the inclusions in size of less than 5 μm that had less than 30 % CaO mainly came from the deoxidation of FeSi alloy with Ca and Al. The inclusions in size of more than 5 μm that had more than 30 % CaO mainly came from the modification of involved slag droplets through the oxidation of Si and Al and the collision with deoxidation-type inclusions, and the degree of change was bigger for smaller inclusions. The MgO in slag and refractory was reduced by Si and Al in steel, which leaded to the unceasingly increase of Mg content in steel. Subsequently, SiO2, MnO and CrOx in inclusion were reduced by Mg, which resulted in the increase of MgO content in inclusion and the degree of increase of MgO content was greater for the larger size of inclusions.

Fluid Flow, Dissolution, and Mixing Phenomena in a Multibottom Tuyere‐Stirred Gas‐Oxygen Refining Furnace

“…[1,2] Its operations have indicated the advantages in terms of high decarbonization rate, high chromium yield, low argon consumption, and high furnace age, etc. [3][4][5][6] In recent years, physical and mathematical simulations have been widely used to study the fluid flow and transport phenomena in metallurgical reaction vessels, such as converters and ladles. The fluid pattern of the gas-liquid flow and the bubble distribution were investigated using the Eulerian volume of fluid (VOF) model and the Lagrangian discrete phase model (DPM).…”

“…[ 1,2 ] Its operations have indicated the advantages in terms of high decarbonization rate, high chromium yield, low argon consumption, and high furnace age, etc. [ 3–6 ]…”

Thermodynamic and Kinetic Analysis for Transformation of Oxide Inclusions in Solid 304 Stainless Steels

“…Evolution of inclusions in 304 stainless steels at production steps have been widely studied . However, less attention has been paid to the variation of inclusions during the heat treatment of stainless steels.…”

Characteristics and Formation Mechanism of Inclusions in 304L Stainless Steel during the VOD Refining Process

“…The control of the composition, quantity, and size of the inclusions at the beginning of their formation is likely to become a new and effective method to reduce the harmful influence of the inclusions. Therefore, it is very important to investigate the source and formation mechanism of the inclusions [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The formation of non-metallic inclusions of Si-killed stainless steel during the GOR (gas oxygen refining) process has been reported by Li et al [7].…”

“…Therefore, it is very important to investigate the source and formation mechanism of the inclusions [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The formation of non-metallic inclusions of Si-killed stainless steel during the GOR (gas oxygen refining) process has been reported by Li et al [7]. The authors found that the inclusions that were larger than 5 µm and contained more than 30% CaO were attributed to the modification of slag droplets through the oxidation of Si and Al and the collision with deoxidation-type inclusions; in addition, the degree of change was larger for the smaller inclusions.…”