Submerged arc welding wire for superstrength pipeline steel and production method thereof

The invention relates to a submerged arc welding wire for superstrength pipeline steel and a production method thereof. The technical scheme is that: the submerged arc welding wire comprises the following components in percentage by weight: 0.04 to 0.06 percent of C, 1.40 to 2.00 percent of Mn, 0.70 to 1.10 percent of Mo, 2.00 to 2.60 percent of Ni, 0.80 to 1.20 percent of Cr, 0.10 to 0.30 percent of Cu, less than or equal to 0.0005 percent of B, less than or equal to 0.01 percent of S, less than or equal to 0.01 percent of P and the balance of Fe and inevitable impurities. The production method comprises the following steps of: adding 0.01 to 0.5 weight percent of composite additive when the components are smelted, forming a square billet in a pouring way, hot-rolling the square billet to form a steel wire rod with the diameter of Phi 5.5 to Phi 7.5mm, removing oxide skin from a surface, drawing the steel wire rod to form the welding wire with the diameter of Phi 3.2 to Phi 4.0mm and performing copper plating, wherein the composite additive is added in form of cored wire. The welding wire produced by the method is welded together with an SJ105 welding flux so as to achieve the tensile strength sigmab of more than or equal to 910MPa and the impact toughness Akv at -30 DEG C of more than or equal to 84J of a weld metal, and is suitable for the submerged arc welding of X120 pipeline steel with superstrength.