According to analysis on the scab defects on the surface of 10B21 boron-containing steel (/% ：0.18 〜 0.23C

≤ l.0Si

0.60 ~0.90Mn

≤ 0.025P

≤ 0.020S

≥0.015 Alt

≥0.008B) wire rod and the surface cracks on the comers of continuous casting billet

by optimizing the composition control of steel (/% ：0.020 ~ 0.050Alt

0.03 〜0.05Ti

≤0.0060N

0.000 8 ~0.0012B)

increasing the drawing speed to 2.3 ~2.4 m/min to ensure the through stretching and straightening temperature of the slab ≥980 ℃；by reducing the specific water strength of the secondary cooling of continuous casting from original 1.29 L/kg to 1.05 L/kg

etc

that can effectively control the comer crack on the surface of continuous casting billet

the scale defect rate is declined from the original 15% to less than 1% after the roiled wire rod.