Effect of calcium treatment on inclusions in 430 stainless steel slabs

The relationships between the calcium mass fraction and the aluminum mass fraction in liquid inclusion region in steel after calcium treatment for 430 ferritic stainless steel was analyzed by the thermodynamic calculation. The inclusion types and number in 430 stainless steel without and with calcium treatment were compared, and the modification mechanism of inclusions was analyzed．The results showed that when calcium silicon line was added during LF, the ideal calcium treatment effect can be obtained. The Al2O3 and CaO-SiO2-Al2O3-MgO inclusion can be modified into inclusions which were liquid at steelmaking temperature after calcium treatment. The inclusion size was less than 15 μm, and the inclusion number was decreased obviously compared with the number without calcium treatment. The CaO and Al2O3 reacted with each other and finally formed liquid calcium aluminates.