Abstract：In order to investigate the modification effect of rare earth elements on inclusions in steel, two kinds of weathering steels, i.e., Q235 without rare earth elements and Q235BRE with rare earth elements, were studied. The inclusions in steels were extracted by nonaqueous electrolytic extraction and physical magnetic separation. Xray diffractometer, scanning electron microscope and energy dispersive spectrometer were used to analyze the types and threedimensional morphology of inclusions. The results showed that the inclusions in Q235 steel without addition of rare earth elements were mainly composed of manganese sulfide and mixed oxide inclusions of aluminum and silicon. The size was relatively large. Irregular polygonal inclusions of magnesium and aluminum oxide and oxygensulfur composite inclusions were up to 40 μm in size, and long strip manganese sulfide inclusions could be 50 μm in size. The inclusions in rare earth weathering steel Q235RE were mainly oxygensulfur rare earth composite inclusions, and the size was obviously smaller. The long strip sulfide was replaced by regular spherical rare earth sulfide and rare earth oxygensulfur complex inclusions. The size of irregular polygonal oxide inclusions was less than 15 μm, decreasing by about 60%.
2022, Vol. 40 
