Effect of Al₂O₃ in refining slag on the cleanliness and fatigue property of ultra-low-carbon automotive steel

The influence of Al₂O₃ content in refining slag on the cleanliness and fatigue property of ultra-low carbon (ULC) automotive steel were investigated based on the industrial experiments. The inclusion adsorption capacity of the refining slag was calculated and the total [O] (T.O) content of ULC automotive steel was measured. The number density, size distribution and morphology of inclusions were analyzed and their effects on the cleanliness and fatigue property of ultra-low-carbon (ULC) automotive steel were investigated. The results showed that as the Al₂O₃ content in refining slag increased from 19.92% to 39.73%, the inclusion-adsorption capacity of ULC automotive steel decreased from 210.30 down to 57.12, and the fatigue life from 1.4x10⁴ down to 0.9x10⁴ cycles, while the T.O content of steel increased from 12 up to18 ppm and the inclusion number density from 4 up to 9 per mm² . (author)