In-situ observation of nonmetallic inclusions in steel using confocal scanning laser microscopy: A review

• CSLM enables real-time observation of inclusion behavior in molten steel, revealing that solid inclusions collide more readily than pure liquid inclusions due to contact angle effects. • Higher CaO/Al2O3 and CaO/SiO2 ratios in slag accelerate the dissolution of Al2O3-based inclusions, while preventing solid phase formation is crucial for efficient inclusion removal. • Combining CSLM with SEM-EDS provides detailed insights into inclusion composition and morphology evolution during steel processing, aiding in inclusion engineering. • The growth rate of acicular ferrites induced by different inclusions follows a specific order at cooling rates of 3–5 K/s, with Ti–O being the slowest and Zr–Ti–Al–O the fastest, guiding inclusion design for improved steel toughness.