Distribution Mechanisms of Surface Inclusions in High Speed Cast Deep-Drawing Steel Slabs
Large non-metallic inclusions(NMIs)on the surface layer of deep drawing steel slabs which cast at high speed were characterized.Method of step-machining within 10mm from the slab surface at the intervals of 0.5mm was employed and the distributions of NMIs larger than 20 microns were evaluated by Aspex Automatic Feature Analysis(AFA)method.In addition,solidification dendrites on the cross-section of slabs were also obtained to elucidate the distribution mechanisms of NMIs across the slab width and thickness.The results show that cluster alumina and bubble associated alumina are the dominant inclusions on the surface layer within 10mm,and no mold powder was detected.Inclusions on the layer of 0.5mm from inner faces concentrated on the slab center because of the deeper hook and low flow velocity.Furthermore,the number density(ND)distribution of macroinclusions in 1/4 width and 1/2 width shows a reverse distribution.Particularly,Surface columnar dendrites which present a special stepwise bending morphology on the slab surface were observed.The ND of large-sized inclusions over 50 microns on slab surface decreases sharply with increasing the flow velocity at the solidification front.It is concluded that some of the macroinclusions at the solidification front are washed out by large steel flow and removed from the dendrites.Accordingly,high speed casting technology can not only meet the high production yield,but also clean up the solid/melt interface and improve the surface cleanliness of slabs.
macroinclusions continuous casting dendrites solidification front wash effect
Xiaoxuan DENG Guosen ZHU Chenxi JI Yang CUI Zhihong TIAN Xinhua WANG
Shougang Research Institute of Technology,Beijing 100043,Beijing,China Shougang Jingtang United Iron & Steel Co.,Ltd,Tangshan 063200,Hebei,China University of Science and Technology Beijing,Beijing 100083,Beijing,China
国际会议
the 6th International Congress on the Science and Technology of Steelmaking,ICS2015(第六届国际炼钢科技大会)
北京
英文
829-832
2015-05-12（万方平台首次上网日期，不代表论文的发表时间）