610MPa grade super-thick steel plate with low welding crack sensitivity and manufacturing method thereof

The invention provides a 610MPa grade super-thick steel plate with low welding crack sensitivity and a manufacturing method thereof. The steel comprises the following components: 0.06-0.10% of C, 0.15-0.40% of Si, 1.40-1.70% of Mn, not more than 0.015% of P, not more than 0.005% of S, 0.10-0.30% of Ni, 0.05-0.10% of Cr, 0.10-0.30% of Mo, 0.10-0.25% of Cu, 0.03-0.05% of Nb, 0.010-0.025% of Ti, 0.015-0.045% of Als and the balance of Fe. The method comprises the steps of smelting, rolling and tempering and is characterized in that two-phase rolling is adopted; the temperature in the full recrystallization rolling phase is 1000-1150 DEG C; the one-pass reduction is more than 10%; the accumulative deformation is not less than 40%; the temperature in the non-recrystallization rolling phase is 840-900 DEG C; the one-pass reduction is more than 12%; the process time from finish rolling to cooling starting is 650-950 seconds; the cooling starting temperature is Ar3+/-30 DEG C; the cooling rate is 5-10 DEG C/s; the finished cooling temperature is 400-510 DEG C; stacking slow-cooling is carried out after rolling; the tempering temperature is 610-650 DEG C; and the tempering time is 4min/mm. The process is simple, the cost is low and the 610MPa grade super-thick steel plate can be produced from single-layer continuous casting slabs.