High-strength, high-toughness and low-yield-ratio pipeline steel plate suitable for wet hydrogen sulfide environment and manufacturing method of high-strength, high-toughness and low-yield-ratio pipeline steel plate

The invention relates to a high-strength high-toughness low-yield-ratio pipeline steel plate suitable for a wet hydrogen sulfide environment. The pipeline steel plate comprises the following chemical components in percentage by weight: 0.03-0.055% of C, 0.20-0.30% of Si, 1.50-1.70% of Mn, 0.02-0.04% of Al, 0.035-0.055% of Nb, 0.01-0.02% of Ti, less than or equal to 0.20% of Cr, 0.20-0.35% of Ni + Mo, less than or equal to 0.0008% of S, more than or equal to 2% of Ca/S and the balance of Fe and inevitable impurities. The tensile strength of the product is larger than or equal to 650 MPa, the impact energy at the temperature of-60 DEG C is larger than or equal to 300 J, the DWTT shearing area at the temperature of-30 DEG C is larger than or equal to 85%, the yield ratio is smaller than or equal to 0.75, and according to the HIC test standard NACE TM0284-2004, the crack length rate is 0%, the crack width rate is 0%, and the crack sensitivity rate is 0% after the product is soaked in a solution A for 96 hours. Th