Subsurface macro-inclusions and solidified hook character in aluminum-killed deep-drawing steel slabs

• Published in: International journal of minerals, metallurgy and materials Vol. 21; no. 6; pp. 531 - 543
• Main Authors: Deng, Xiao-xuan, Li, Lin-ping, Wang, Xin-hua, Ji, Yun-qing, Ji, Chen-xi, Zhu, Guo-sen
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.06.2014; Springer Nature B.V; School of Metal urgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China%Shougang Research Institute of Technology, Shougang Group, Beijing 100041, China
• Subjects: Aluminum; Aluminum killed steels; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Deep drawing; Glass; Hooks; Inclusions; Low carbon steels; Materials Science; Metal sheets; Metallic Materials; Natural Materials; Slabs; Steel; Surface properties; Surfaces and Interfaces; Thin Films; Tribology; X-ray spectroscopy; 固化; 夹杂物; 字符; 宏观; 扫描电子显微镜; 深冲钢板; 钢板坯; 镇静; steel sheet; low carbon steel; hooks; aluminum-killed steel; inclusions; deep drawing
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-014-0939-0

Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ultralow carbon （ULC） steel slabs and two low carbon （LC） aluminum-killed steel slabs were sampled to study the relationship between hooks and subsurface macro-inclusions, which were detected on the cross-sections of steel samples with an area of 56058 mm2 using an automated scanning electron microscopy/energy-disper-sive X-ray spectroscopy system. Results show that subsurface inclusions larger than 200 μm were almost entrapped by hook structures, whereas the location of other inclusions smaller than 200μm had no obvious dependence on the location of solidified hooks. Furthermore, the number density （ND） of subsurface inclusions larger than 200μm decreased from 0.02 to 0 cm-2 in ULC steel as the mean hook depth decreased from 1.57 to 1.01 mm. Similar trends were also observed in LC steel. In addition, the detected inclusions larger than 200μm were concentrated in the region near the slab center （3/8 width-5/8 width）, where hook depths were also larger than those at any other locations. Therefore, minimizing the hook depth is an effective way to reduce inclusion-induced sliver defects in deep-drawing steels.