Forming mechanism and improvement measures of short line defects on IF steel car outer plate
WANG Chang1,2, YU Yang1,2, NI You-jin3, WANG Lin1,2, FU Guang3, LI Jin-bao3
1. Shougang Thin Plate Research Institute of Technology, Shougang Group Corporation, Beijing 100043, China; 2. Beijing Key Laboratory of Green Recyclable Process for Iron and Steel Production Technology, Beijing 100043, China; 3. Manufacturing Department, Shougang Corporation, Qian'an 064404, Hebei, China
Abstract：In order to reduce short line defects on IF steel car outer plate, the formation mechanism of short line defects were studied in detail based on indefinite chill double pour (ICDP) roll microstructure and its oxidation characteristics by means of thermogravimetric analyzer, scanning electron microscope and electron microprobe analyses. The results show that the short line defects on car outer plate surface of IF steel show scar morphology, and there are oxide film residue in the cracking area around the scar. Trace elements in the scar show the characteristics of high nickel, low chromium and low silicon, which is corresponding to the surface composition of ICDP roll obviously. There are some problems in ICDP roll, such as incomplete spheroidization of graphite phase and poor size uniformity of wear resistant particles. Therefore, short line defects are considered to be mainly caused by oxide film spalling and thermal fatigue cracking of ICDP roll during rolling. The defects can be effectively controlled through the improvement measures such as optimizing hot rolling scheduling system and finishing mill load, strengthening control of roll quality, roll cooling water and lubricant, and improving roll surface quality.
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WANG Chang, YU Yang, NI You-jin, WANG Lin, FU Guang, LI Jin-bao. Forming mechanism and improvement measures of short line defects on IF steel car outer plate[J]. China Metallurgy, 2022, 32(10): 97-104.
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2022, Vol. 32 
