Abstract:

The experiment of magnesium treatment of high strength rebars containing Ti was carried out by vertical resistance furnace in the laboratory. The changes of composition and size of inclusions of the samples before and after magnesium treatment were analyzed, and the formation and precipitation of inclusions were calculated using FactSage software. The results showed that the inclusions of the sample before Mg addition were Al₂O₃、TiN-Al₂O₃ and TiN, and after Mg treatment, the inclusions were Al₂O₃、MgO·Al₂O₃、TiN-Al₂O₃、TiN-MgO·Al₂O₃ and TiN. It was easy to form Al₂O₃ in the steel with high oxygen content, on the contrary, the MgO was formed easily. And, It was difficult to form MgO inclusion in the steel containing higher Al content. TiN inclusion could be precipitated on the oxide or just precipitated during solidification of steel. The size of inclusion decreased after magnesium treatment. The MgTi₂O₄ inclusion was mainly formed under the condition of the steel with high Mg content and low temperature, and this kind of inclusion in the sample was mainly precipitated during solidification.

Key words: rebars, Mg treatment, inclusion, precipitate