The invention discloses novel preheating-
welding-free high-strength steel HPDB700 and a production method thereof, the novel preheating-
welding-free high-strength steel HPDB700 comprises the following chemical components in percentage by weight: 0.07-0.09% of C, 0.20-0.35% of Si, 1.55-1.65% of Mn, less than or equal to 0.010% of P, less than or equal to 0.003% of S, 0.025-0.035% of Nb, 0.30-0.40% of Cr, 0.02-0.05% of Als, 0.0012-0.0018% of B and the balance of Fe and inevitable
impurity elements, the carbon equivalent Ceq of the novel preheating-
welding-free high-strength steel HPDB700 is less than or equal to 0.43%, and the crack
sensitivity coefficient Pcm of the novel preheating-welding-free high-strength steel HPDB700 is According to the steel plate, precious
alloy elements such as Ni, Mo and Cu are not added, through the composition proportion of C, Mn, Nb and B, on one hand, the
alloy cost is reduced, and on the other hand, due to the fact that
hardenability alloy elements such as Ni and Mo are not added, the
hardenability of the steel plate is reduced, the welding cold crack tendency is reduced, and normal-temperature welding is facilitated; through the
process innovation of DQ
water cooling and
slow cooling, the steel plate does not need
tempering or
tempering, the production cost is low, the efficiency is high, the production process is simple and easy to operate, and the method is very suitable for continuous
mass production.