To provide a method for producing a taper plate having a tensile strength of 570 MPa or more, to which high heat input welding having a welding heat input exceeding 300 kJ/cm can be applied.
A steel slab contains, by mass, 0.03 to 0.12% C, 0.03 to 0.5% Si, 0.8 to 2.2% Mn, 0.015% or less P, 0.0005 to 0.0050% S, 0.005 to 0.1% Al, 0.003 to 0.014% Nb, 0.003 to 0.02% Ti, 0.0003 to 0.0025% B, 0.0030 to 0.0070% N, 0.0005 to 0.005% Ca, satisfies formula (1), with the balance consisting of Fe and unavoidable impurities. The steel slab is heated to 1000°C to 1200°C and then subjected to hot rolling in which the plate thickness varies in a tapered shape in the longitudinal direction at a rolling finish temperature of 900°C or less and an Ar3 point or above, followed by accelerated cooling to 500°C or less. Formula (1): 0≤N-Ti/3.42≤0.0025, wherein N and Ti are the content (mass%) of each component.
YOKOTA TOMOYUKI
NAKAMURA MASAMI
MITAO SHINJI
| JP2000303147A | 2000-10-31 | |||
| JP2007051321A | 2007-03-01 | |||
| JPH08232016A | 1996-09-10 |
Kazuhiro Mori