The metallurgical flowsheet of 160 angle steel Q420C with 18 mm thickness for power tower (/% : ≤0.20C

1.00〜1.70Mn

≤0.55Si

≤0.035S

≤0.035P

0.02~0.20V

≥0.015Als) is 80 t BOF-LF-CC-rolling process. The analysis on comer cracks of hot-rolled angle steel is carried out by optical microscope

scanning electron microscope and energy dispersive spectroscopy. The results show that there are decarburized layer and ferrite film around cracks

the S enrichment near cracks and the AIN precipitates at grain boundary are found that break the continuity of steel matrix. It is obtained that the slag inclusions at oscillation mark bottom

segregation

thermal stress and bending straightening stress lead to angle steel crack along grain boundary. With process measures including decreasing [N] to 0.0080%

controlling Als 0.017%~0.022%

[Mn]/[S] ≥80

liquid over heating extent ≤25°C

viscosity of mold powder 0.73 Pa·s

and straightening temperature ≥950°C

the quality cast billet increases to 85% from original 25.78%

it is available to decrease the occurrence of comer cracks of angle steel.