Thick-gauge x80 pipeline steel plate with excellent ultra-low temperature drop weight performance and manufacturing method thereof

The invention discloses a thick-specification X80 pipeline steel plate excellent in ultralow-temperature drop hammer performance. The thick-specification X80 pipeline steel plate comprises, by mass, 0.02%-0.06% of C, 1.45%-1.6% of Mn, 0.1-0.35% of Si, 0-0.0006% of S, 0-0.010% of P, 0.055%-0.08% of Nb, 0.008%-0.03% of Ti, 0-0.008% of V, 0-0.06% of Alt, 0-0.0040% of N, 0-0.004% of O, 0-0.30% of Mo, 0-0.0015% of Pb, 0-0.003% of Zn, 0-0.0015% of Sb, 0-0.0015% of Sn, 0-0.30% of Cu, 0.20%-1.5% of Ni, 0-0.35% of Cr, 0-0.01% of Ca, the balance Fe and inevitable impurity elements, and the sum of the Mo, the Cu, the Ni and the Cr is less than or equal to 1.5%. The thickness of the steel plate is 30 mm or above. The manufacturing process of the thick-specification X80 pipeline steel plate comprises the following steps of proportional material preparing, converter or electric furnace smelting, external refining, continuous casting, plate blank reheating, conducting of specific TMCP technology, stack cooling after cooling and strengthening. According to the thick-specification X80 pipeline steel plate excellent in the ultralow-temperature drop hammer performance and the manufacturing process, the low-temperature toughness of the X80 pipeline steel plate is further improved, especially, the ultralow-temperature drop hammer performance of the steel plate is remarkably improved, and the yield is high.