Continuous casting method and continuous casting machine for steel

A continuous casting machine for steel,

• the machine being a curved type continuous casting machine or a vertical bending type continuous casting machine for continuously casting steel,
• the machine comprising:
• a soft reduction zone where a cast piece to be continuously cast is rolling-reduced in a thickness direction, wherein
• in the soft reduction zone, the rolling reduction is applied to the cast piece at a rolling reduction rate of 0.3 mm/min or more and 2.0 mm/min or less in a range where a center solid phase ratio being a solid phase ratio in a thickness center of the cast piece is at least 0.2 or more and less than 1.0, and
• a segment deflection T being a deflection in the thickness direction of a segment frame of a segment where the rolling reduction is applied to the cast piece in the soft reduction zone satisfies Equation (1),
• 2
• ×
• ⊤
• -
• A
• /
• (
• n
• -
• 1
• )
• ≤
• 3
• .
• 2
• ⁢
• 5
• ×
• 2
• ×
• δ
• ≤
• 1.3
• (
• 1
• )
• wherein
• δ represents an actually measured bulging amount (mm),
• τ represents a segment deflection (mm),
• A represents a set rolling reduction amount of soft reduction in the soft reduction zone where the center solid phase ratio of the cast piece is 0.2 or more and less than 1.0 (mm), and
• n represent a number of cast piece supporting roll pairs present in the soft reduction zone where the center solid phase ratio of the cast piece is 0.2 or more and less than 1.0.