Abstract: The generation plasticization control of CaO-Al2O3-SiO2-MgO inclusions was discussed by thermodynamic calculation, and the effect of the top slag composition on inclusions was studied in the lab and industry. As a result, in the CaO-Al2O3-SiO2-MgO(10 %) diagram, when w（CaO）=8 %~48 %, w（SiO2）=35 %~75 %, w（Al2O3）=0~32 %, inclusions were in plastic zone. With the increase of the content of Al2O3 in the slag, the content of Al2O3 in inclusions of tire cord steel increased. And the distribution of inclusions became scattered with the mass fraction of Al2O3 increasing in the slag. Combined with laboratory results and industrial trials, when the basicity of top slag between 0.7 and 0.9, w (Al2O3) s=2 %~5 %, the non-metallic inclusions in steel could be plastified and wire breaking reduced by 30 % through the composition of refining slag controlling, so as to the quality of wire rod improved.

Key words: tire cord steel, top slag, plasticity, inclusions