PMET_08: Steel Deoxidation on Tapping

This application example, which is available on our website and uses the Process Metallurgy Calculator, shows a few of the ways the Process Metallurgy Module in Thermo-Calc can be used to investigate steel deoxidation (killing) on tapping.

About Deoxidation or “Killing” of Steel

Deoxidation of steel, also known as killing of steel, occurs toward the end of the steelmaking process, but before desulphurization. After primary steelmaking, for example in a basic oxygen furnace (BOF) or electric arc furnace (EAF), the liquid steel contains a large amount of dissolved oxygen [O] (400 to over 1000 ppm.) (see PMET_04: Basic Oxygen Furnace (BOF) Kinetics).

This oxygen must be removed from the liquid steel for several reasons, including:

  • Desulphurization is not effective with high oxygen content in the steel
  • Continuous casting of un-killed steel is not possible and will result in “boiling” of the steel in the mould and massive porosity.

The two most widely applied methods of deoxidizing or killing the steel are adding Al to the steel (Al-killed steel) and adding Si to the steel (Si-killed steel). In this example we look at how the Process Metallurgy Module in Thermo-Calc can be used to investigate these two widely applied methods of deoxidizing or killing the steel.

The two most widely applied methods of deoxidizing or killing the steel are adding Al (Al-killed steel) to the steel and adding Si (Si-killed steel) to the steel. These elements readily react with oxygen to form oxides that precipitate within the liquid steel. This does not reduce the total amount of oxygen in the liquid steel; it simply transforms the dissolved oxygen into an oxide precipitate. This oxide precipitate then needs to be removed from the steel by flotation during secondary metallurgy in the ladle furnace (LF).

This, however, can result in the formation of damaging inclusions that cause problems during further processing, so we go on to look at two simple and very common processes that are used to transform the solid SiO2 and Al2O3 inclusions into liquid oxides so that they are less damaging.

  • Folder: Process Metallurgy
  • File name: PMET_08_Steel_Deoxidation_on_Tapping.tcu

Choose a or b versions of the example based on your license.

  • PMET_08a_Steel_Deoxidation_on_Tapping.tcu is included in a regular Thermo-Calc installation as well as the free Educational version of Thermo-Calc. It is a simplified version that uses the OXDEMO database.
  • PMET_08b_Steel_Deoxidation_on_Tapping.tcu requires a full license of Thermo‑Calc version 2021b or newer and database TCOX11 or newer.

Visualizations

Many of our Graphical Mode examples have video tutorials, which you can access in a variety of ways. When in Thermo‑Calc, from the menu select Help → Video Tutorials, or from the main My Project window, click Video Tutorials. Alternately, you can go to the website or our YouTube channel.

Open the example project file to review the node setup on the Project window and the associated settings on the Configuration window for each node. For some types of projects, you can also adjust settings on the Plot Renderer Configuration window to preview results before performing the simulation. Click Perform Tree to generate plots and tables to see the results on the Visualizations window.

The resulting plots and details related to setting up this example are available to download via the dedicated web page.