IF 钢铸坯厚度方向洁净度演变

采用夹杂物原貌分析、扫描电镜和能谱分析、氧氮分析等手段系统分析了 IF 钢铸坯全厚度方向的洁净度变化及夹杂物分布规律.铸坯厚度方向全氧(T. O)和 N 质量分数平均值均为17×10-6.内、外弧表层1/16内 T. O、N 均高于平均值5%~10%,存在夹杂物聚集带；内弧1/4至外弧1/4区域 T. O、N 水平低于平均值5%~10%；表层1/16至1/4区域接近平均水平.共统计夹杂物963个,夹杂物平均粒径5.7μm,<5μm 占60%, < 10μm 占90%；Al2 O3夹杂主要存在表层5 mm 内,尺寸在2~10μm；TiN- Al2 O3和 TiN 粒子主要在距离表层5 ~ 80 mm,尺寸随深度增加而增大；TiN- TiS 和 TiS 夹杂主要在距离表面80~130 mm,尺寸1~5μm.从铸坯表层到中心主要夹杂物的分布依次是 Al2 O3、Al2 O3- TiN、TiN、TiN- TiS、TiS 和 MnS.

Cleanliness evolution of interstitial free (IF) steel slabs in the thickness direction

The cleanness evolution and inclusion distribution of IF slabs in the thickness direction were studied by original mor-phology analysis, scanning electron microscopy and energy spectroscopy analysis, and total oxygen (T. O) and nitrogen analysis. The average values of mass fraction of total oxygen and N in the slabs in the thickness direction are within 17 × 10 - 6 . The mass fractions of T. O and N in the area within 1 / 16 thickness from the slab surface are 5% to 10% higher than the average values, in the area between 1 / 4 thickness from the inner arc and 1 / 4 thickness from the outer arc are 5% to 10% lower than the average values and in other area are close to the average levels. The average size of inclusions is 5. 7 μm based on a total of 963 statistical inclusions. Inclusions with the particle size smaller than 5 μm account for 60% and with the particle size smaller than 10 μm account for 90% . Al2 O3 mainly exits within 5 mm from the slab surface with the size of 2 to 10 μm; TiN- Al2 O3 and TiN exist in the area from 5 to 80 mm in the thickness direction, and their particle size grows up as the thickness increasing; TiN- TiS and TiS inclusions mainly exist in the area from 80 to 130 mm in the thickness direction with the size of 1 to 5 μm. Inclusions from the slab surface to center are mainly Al2 O3 , Al2 O3- TiN, TiN, TiN- TiS, TiS, and MnS in order.