Abstract: The effects of traditional VD high-alumina process (high-aluminum molten steel inlet) and the VD aluminum-adjusting process (low aluminum molten steel inlet, adjusting aluminum after vacuum breaking) on the purity of Q355 wind power steel molten steel was compared. It was found that the VD aluminum-adjusting process significantly improved molten steel quality and reduced aluminum costs. The tests showed that the number density of inclusions decreased by 51.8% during the VD inlet stage under the VD aluminum-adjusting process, and the area fraction of inclusions decreased by 29.8% during the casting stage. Simultaneously, the proportion of Al₂O₃ in inclusions decreased substantially by 33.35%, while the CaO proportion increased, promoting the transformation of CA₂-C₁₂A₇ into C₁₂A₇. Consequently, the average B-type coarse inclusion rating on the steel plate decreased by 45%. The mass fraction of total oxygen decreased by 11.8%–24.8% across various stages in steel, while desulfurization efficiency decreased more moderately due to the lower aluminum content. In terms of cost, aluminum consumption decreased from 3.09 kg/t to 2.67 kg/t, saving 7.56 yuan/t. The results indicate that the VD aluminum-adjusting process delivers significant improvements in enhancing molten steel cleanliness and economic efficiency.

Key words: VD aluminum-adjusting process, inclusions, total oxygen content, denitrogenation efficiency, desulfurization efficiency, cost