The invention discloses a method for raising large heat input
weldability of a thick steel plate, comprising the following steps: 1)
smelting and
casting to form a steel plate: adding deoxidizers in the deoxidation process of the
liquid steel according to the following types and order: Mn, Si, Al, Ti, and Ca and / or Mg, controlling the initial
oxygen place in the
liquid steel when Mn deoxidation is carried out in
casting, adding Fe2O3
powder to let the
oxygen content in the
liquid steel be 0.001-0.008 wt%, wherein, the steel plate comprises 0.05-0.09 wt% of C, 0.10-0.30 wt% of Si, 1.3-1.7 wt% of Mn, 0.005-0.02 wt% of Ti, no larger than 0.015 wt% of P, no larger than 0.01 wt% of S, no larger than 0.006 wt% of N, no larger than 0.004 wt% of Ca, and the balance consisting of Fe; in the steel, the volumn density of
TiN deposition with the particle size of less than 500 nm is larger than 9.0*107 PCs / mm<3>, the average particle size is less than 80 nm, and the proportion of the deposition with the particle size of less than 100 nm is larger than 75 %; 2) rolling and cooling. The large amount of nano
TiN deposition with dispersive distribution formed by the invention can inhibit the growth of
austenite crystals in the
heat affected zone, and greatly raise the large heat input
weldability of the thick steel plate.