The Development of Steel-making Processes for Improving H-beam Surface Quality

by Yu Zen Chen, Chia Hao Wu

Publisher - Dragon Steel Corporation

Category - General Novel

Dragon Steel Corporation (DSC) as subsidiary of China Steel Corporation produced H-beam rolled by beam blanks using EAF-LF steelmaking process and semi-open casting. To satisfy the requirements of the rising local and overseas infrastructure, the surface defects of H-beam such as flange corner lap and seam which were highly related with steel-making process must be solved. The approaches of the processes were sequentially introduced as: 1) Hot metal charging, 2) VD refinement, 3) fully shrouding casting. At first, hot metal charging operation reduced the harmful residual elements such as copper and tin which cause the hot-shortness on beam blanks. Secondly, the implement of VD refinement didn’t only diminish gas efficiently but increase the steel cleanliness. The blowholes, which caused flange corner lap, on beam blanks and seam on H-beam were improved through the de-hydrogen reaction and inclusion removal. For the sake of high quality demand, the original open casting was replaced by shrouding casting practice to avoid secondary oxidation. The further steel cleanliness enhancement resulted in elimination of the seam on H-beam. Consequently, the ratio of H-beam surface defects resulting from steel-making process has decreased 90%, which brings remarkable profits.

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