Abstract: The metallurgical flowsheet of weathering steel S355J2 (/% : 0. 07 ~0. 12C, 0.25 ~0. 40Si,1.0 ~1. 3Mn, ≤0. 015P, ≤0. 008S,0. 25 ~0. 40Cu, 0. 35 ~0. 50Cr, 0. 10 〜0. 25Ni, 0. 025 ~ 0. 040Nb, 0. 025 ~0. 050Als) is 70 t LD-LF-VD-280 mm x 320 mm bloom CC process. With the process measures including controlling LD end [C]≤0. 07% , end [P] ≤0. 014% , converter tapping slag amount ≤2 kg/t, and refining slag basicity R ≥3.0 and (A1₂O₃)= 20% , the T[O] in casting bloom is 22 x 10 ^-6, average diameter of inclusions is 4. 6 μm with ratio of less than 5 μm inclusions more than 97. 5%. By using the bearing fluorine mold powder with basicity = 1. 02, 6. 9% ( B₂O₃+ Li₂0), 5. 4% MgO and 7. 6% A1₂O₃, the bloom oscillation mark is slight, and the ratio of bloom surface without cleaning is up to 95. 17% . The rating of shrinkage and porosity of bloom ≤l. 0, and the rating of crack at comer, edge and center of bloom is 0 to meet the control requirement of bloom quality.

Key words: 70 t LD-LF-VD-CC, , Weathering Steel S355J2, , Metallurgical Quality, , Inclusions

摘要： 耐候钢S355J2(/%:0.07~0.12C,0.25~0.40Si,1.0~1.3Mn,≤0.015P,≤0.008S,0.25~0.40Cu,0.35~0.50Cr,0.10~0.25Ni,0.025~0.040Nb,0.025~0.050Als)的冶炼流程为70 t LD-LF-VD-280 mm×320 mm坯CC工艺。通过控制LD终点[C]≤0.07%,终点[P]≤0.014%,转炉下渣量≤2 kg/t和LF精炼渣碱度R≥3.0,(Al₂O₃)=20%等工艺措施,铸坯的T[O]为22×10^-6,夹杂物平均直径为4.6μm,5μm以下夹杂物比例在97.5%以上。连铸过程采用R=1.02,6.9%(B₂O₃+Li₂O),5.4%MgO和7.6% Al₂O₃的含氟保护渣,连铸坯表面震痕较浅,表面无清理率达到95.17%。连铸坯缩孔、疏松≤1.0级,角部、边部和中心裂纹为0级,满足连铸坯质量的控制要求。

关键词: 70 t LD-LF-VD-CC, , S355J2耐候钢, 冶金质量, 夹杂物