Research on Inclusions in Non-quenched and tempered Sulfur-bearing Steel for Autos

Inclusions in different specimens of non-quenched and tempered sulfur-bearing steel for autos were analyzed with metallographic microscope,scanning electron microscope and energy-dispersive X-ray detector.The result shows that the inclusions in this kind of steel are dominantly in shape of strip,spindle and sphere,distributed dispersedly or in clusters.The inclusions are mainly pure MnS with a small amount of compound inclusions(with core of oxides and nitrides coated with sulfides) and little separate Al₂O₃ and TiN.The compound inclusion are primarily spindle and sphere-shaped(above 90% of them have a length-width ratio of less than 3).Cored or concomitant compound inclusions account for 25% of all the spindled sulfides.High oxygen is ravorable to forming compound sulfides.