X90 line pipe with uniform deformation elongation UEL more than or equal to 5 percent and preparation method thereof

The invention provides an X90 line pipe with uniform deformation elongation more than or equal to 5 percent. The line pipe is prepared from the following chemical components in percentage by weight: 0.040-0.060 percent of C, 1.60-1.80 percent of Mn, 0.35-0.65 percent of Cr, 0.05-0.15 percent of Mo, 0.15-0.25 percent of Ni, 0.060-0.080 percent of Nb, less than or equal to 0.009 percent of P and less than or equal to 0.00095 percent of S. The X90 line pipe is prepared in the following steps: deep desulfurizing, dephosphorizing and the like; heating a slab; roughly rolling; precisely rolling; cooling; air cooling to room temperature; performing a tubulation process; and preparing a longitudinal submerged arc welding tube by bent forming and heat input welding, expanding diameter of the steel tube, and controlling the expansion rate of 0.20-0.60 percent. According to the X90 line pipe, the steel tube can be plasticized, which means that the UEL is more than or equal to 5 percent on the premise that the mechanical performances RP0.2 of more than or equal to 650MPa, Rm of more than or equal to 730MPa, KV2 at minus 20 DEG C of more than or equal to 280J and DWTTSA at minus 15 DEG C of more than or equal to 85 percent are met, so that super-high toughness and high plasticity can be excellently matched.