Analysis of the Causes of Localized Carbon Increase on the Shallow Surface of Medium Carbon Steel SWRCH35K Coils
Analyzing the reasons for the"inverted triangular"pearlite segregation on the shallow surface of SWRCH35K wire rod,it was found that there was local carbonization on the shallow surface of the casting billet,with a carbonization rate of 26.19％,of which the comer accounted for 68.18％.Study the effects of crystallizer protective slag,intermediate plug rod,immersion nozzle and steel inlet structure,and crystallizer electromagnetic stirring parameters on the occurrence rate of surface carbonization of castings.After optimization,the alkalinity of the protective slag decreased by 0.11,the melting rate decreased by 3 seconds,the melting point increased by 25 ℃,and the viscosity increased by 0.08 Pa·s.The thickness of the protective slag layer after optimization was 8～11 mm.It has developed and applied a continuous casting intermediate ladle plug core insulation device,a repair method for the steel mouth lining of the intermediate ladle,and a special brick.At the same time,it has optimized the design of the immersion water outlet bowl and lining to achieve precise flow control of the plug,ensuring the long service life of the intermediate ladle and immersion water outlet,and reducing the occurrence rate of abnormal liquid level fluctuations in the crystallizer.Based on the above optimization results,the electromagnetic stirring parameters of the crystallizer were reduced from 350 A and 3 Hz to 200 A and 2 Hz,achieving a fluctuation of±3 mm in the crystallizer liquid level and a decrease in the occurrence rate of surface carbonization of the casting billet from 26.19％to 3.57％.
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