Φ1200 mmS355NL/Q355NE steel (Ceq0.38-0.41) continuous casting round bloom is manufactured by 100 t KR-BOF-LF-RH-R18M continuous casting process. Full protective casting

precise cooling process

three-stage electro- magnetic stirring

slow cooling process and other technical measures are adopted. The superheat is controlled at 1545 ℃

the drawing speed is 0.14-0.20 m/min

the electromagnetic stirring is 300 A/2 Hz

the secondary cooling water ratio is 0.20 L/kg

the slow cooling time into the pit is ≥72 h

and the pit exit temperature is ≤300 ℃. The results show that [0]≤0.0018%

[H]≤0.00008%; the central porosity of cast bloom≤1.5  rating

the central crack≤1.5 rating

the shrinkage cavity ≤0.5 rating

and the carbon content range of the whole section≤0.07%. Chemical composition

macrostruce

surface quality all meets the standard requirements. After the round bloom is forged into wind turbine flanges with wall thickness of 450-550 mm by customer

the test results of inclusions

mechanical properties

internal flaw detection and other quality indexes are satisfactory

which fully meet the technical specifications and user requirements.