Control Of Oxygen, Nitrogen And Hydrogen In Induction Melted Steels

JCC-Canhu continues to make an effort geared towards producing castings free of non-metallic inclusions, with gas control and removal remaining a critical aspect of the production process. Foundry produced Mill Liners through different gas control and removal methods, emphazie the importance of gas removal and control in furnace to reduce gas related defects in steel castings.

At the end of the last century, it was discovered that there are large amounts of gas inclusions in carbon steel and low alloy steel. They used a melting and pouring practice that includes medium frequency induction furnaces and lip pour ladles. The furnaces were lined with a spinel bond fused alumina-based refractory, while the ladles were lined with fused alumina-based castable refractory materials.

Early this century, engineers found that insufficient or inefficient deoxidation was the main cause of gas porosity in steel castings. In order to increase the filter blockage factor, the amount of aluminum used for deoxidation must be drastically reduced, and another additional final deoxidizer was needed.

Gas control in steel castings is crucial in ensuring high-quality results. While controlling gases is more challenging in induction melting furnaces, continuous efforts to reduce gas-related defects must be made. The final deoxidizer, whether titanium or aluminum, is just a part of the solution. The study also revealed that it is always better to scrap a casting in its early stage than a partially machined one to avoid tooling damage caused by filter breakage.