• Supergravity fields achieve extreme removal of fine SiO2 and MnO inclusions from 304 stainless steel, with total oxygen content reduced from 240 to 28 ppm (88.33% removal) at gravity coefficient 500 and 600 s.
• Inclusions migrate to the top of the sample and form large aggregates, while the bottom becomes significantly purified, showing a gradient distribution of inclusion volume fraction and number density.
• The method outperforms conventional techniques (electroslag remelting, gas stirring, ceramic filtration) in removing small inclusions, offering a more effective and efficient purification approach.
• The findings provide a promising industrial pathway for producing ultra-clean steel with enhanced mechanical properties and corrosion resistance.