Heavy plate and thermomechanical treatment method for a starting material for the production of the heavy plate

A thermomechanical treatment method for a starting material for the production of a heavy plate consisting of a steel alloy, containing the following, each in wt %:

• 0.01 to 0.20
• carbon (C),
• 0.5 to 2.50
• manganese (Mn),
• 0.05 to 0.80
• silicon (Si),
• 0.01 to 0.20
• aluminum (Al),
• <0.05
• phosphorus (P),
• <0.01
• sulfur (S),
• and optionally individual elements from the following group or combinations thereof:
• 0 to 1.5
• chromium (Cr)
• 0 to 1.0
• molybdenum (Mo)
• 0 to 1.0
• copper (Cu)
• 0 to 5.0
• nickel (Ni)
• 0 to 0.30
• vanadium (V)
• 0 to 0.20
• titanium (Ti)
• 0 to 0.20
• niobium (Nb)
• 0 to 0.005
• boron (B)
• 0 to 0.015
• nitrogen (N)
• 0 to 0.01
• calcium (Ca)
• and residual iron (Fe) and inevitable production-related impurities, which treatment method comprises the following steps:
• heating the starting material to above the Ac3 temperature and partial forming the starting material using a first rolling procedure,
• accelerated cooling of the starting material after the first rolling procedure from a first final rolling temperature to below the Ar3 temperature
• heating the starting material after the accelerated cooling to a second initial rolling temperature for a second rolling procedure above the Ac3 temperature and final forming of the starting material by the second rolling procedure to a thickness of the heavy plate and
• multi-stage cooling optionally with at least one straightening procedure after the final forming in that
• a cooling from a second final rolling temperature of the second rolling procedure to a first temperature between 250 and 500° C., is carried out at a first cooling rate in a first stage after the second rolling procedure, and
• a cooling of the starting material to room temperature is carried out at a second cooling rate in a subsequent second stage,
• wherein a straightening procedure is carried out after the first stage,
• and wherein the first cooling rate is >the second cooling rate.