Abstract： In order to decrease the edge crack ratio of YQ450NQR1 Zsteel，the typical edge crack defects’ morphology and microstructure was tested and key influence factors of the edge crack’s formation were studied. The results show that the edge cracks were formed from the primary crack in blooms which deformed and expanded during the rolling process. The root cause is the mold flux had a poor heat transfer lubrication which led to the uneven width and excessively depth of oscillation marks，and the straightening temperature of the bloom corner was in the brittle temperature zone. An optimized physical parameters index of the mold flux is found which can improve the lubrication and the heat transfer obviously. The width of oscillation marks is improved from 3-10 mm to 7-9 mm，and the depth of oscillation marks is improved from 1.0-1.5 mm to less than 1.0 mm. The cracks in the bloom corner and slag pit defects are eliminated. The continuous casting cooling process is also optimized，and the brittle temperature zone is avoided during the straightening process. The edge crack ratio is reduced from 21.80%-22.28% to 0.59%. Results provides some reference for the control of the edge crack in the high strength and high weathering steel YQ450NQR1.
李红光，邓通武，陈亮，郭跃华. YQ450NQR1高强高耐候乙字钢边裂分析与控制[J]. 钢铁, 2019, 54(8): 169-173.
LI Hongguang，DENG Tongwu，CHEN Liang，GUO Yuehua. Analysis and control of edge crack in high strength and #br#
high weathering steel YQ450NQR1. Iron and Steel, 2019, 54(8): 169-173.