Exploration of morphology evolution of the inclusions in Mg-treated 16MnCrS5 steel

ABSTRACTTo elucidate the morphology evolution of the inclusions in 16MnCrS5 steel with various masses of Mg addition, the experiments and thermodynamics were carried out with a high-temperature tube electric resistance furnace and FactSage software, respectively. The evolutions of the inclusions after the smelting and hot-processing were described. The experimental results show that with Mg addition of 35–42 ppm, many spindle and spherical inclusions with the size below 20 μm appeared, whereas the long-strip inclusions above 20 μm disappeared; after hot-processing, particularly, the h value was above 50%, beneficial to obtaining more spindle inclusions, and most spherical inclusions at 35 ppm were also obtained. The thermodynamics show that with Mg mass between 0.349 and 6.076 ppm, Al2O3 was easily converted to MgO·Al2O3, whereas above 6.076 ppm, Mg was directly converted to form MgO; above more, MgS coexisted with MgO.