关键词: 31CrMoV9钢, CaO-SiO₂-Al₂O₃-MgO-CaF₂系精炼渣, 碱度, Al₂O_3, , 夹杂物

Abstract: Tested steel 31CrMoV9 (/% : 0.28 ~0.33C, 0.30 ~0.35Si, 0.49 ~0.60Mn, 0. 011 ~0.016P, 0.027 ~ 0.031S, 2.47 ~2.60Cr, 0. 16 ~0.23Mo, 0. 12 ~0. 19V) is melted by a 25 kg induction furnace, and the effect of binary basicity 2.5 ~ 3.5 of different ingredient refining slag (/% : 46.43 - 59. 89CaO, 15.16 - 23.50Si0₂, 10 〜20Al₂O₃, 6 〜 10MgO, 2 ~5CaF₂) on number, size and composition of inclusions in steel 31CrMoV9 has been studied by orthogonal experiment method. Results show that the effect of binary basicity and alumina content in refining slag on inclusion content in this steel is obvious ； as the binary basicity of slag increases from 2.5 to 3.5, for per 0.3 mm² steel the average area of inclusions increases from 22.07 μm² to 25.67 μm²  i. e. that increases by 16.31% and the number of inclusions decreases from 316.67/0.3 mm² to 255.00/0. 3 mm², i. e. that decreases by 19. 47% , it is available to form composite inclusions； as alumina content in slag increases from 10% to 20% , for per 0. 3 mm² steel the area of inclusions increases from 22. 57 μm² to 24. 28 μm², i. e. that increases by 7. 55% and the number of inclusions decreases from 292. 67/0.3mm² to 272.00/0.3 mm², i. e. that decreases by 7. 06% , it is available to form aluminium-magnesium spinal inclusions. With comprehensive analysis the refining slag contained 10% Al₂O₃ , 10% MgO and 5% CaF₂ with binary basicity 3.5 has better refining effect.