890MPa-grade coating-free atmospheric corrosion-resistant bridge steel and preparation method thereof

The invention relates to 890MPa-grade coating-free atmospheric corrosion-resistant bridge steel and a preparation method thereof. The bridge steel is composed of the following elements in percentage by mass: 0.095%-0.155% of C, 0.15%-0.25% of Si, 1.60%-1.95% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.40%-0.70% of Cr, 0.25%-0.30% of Cu, 0.60%-1.50% of Ni, 0.20%-0.30% of Mo, 0.045%-0.075% of Nb, 0.008%-0.025% of Ti, 0.020%-0.040% of Re, 0.0030%-0.0050% of O, 0.015%-0.045% of Als and the balance of Fe and inevitable impurities, and the chemical components need to meet the (2) I > = 6.75; the yield strength of the steel is larger than or equal to 915 MPa, the tensile strength is larger than or equal to 1025 MPa, the yield ratio is smaller than or equal to 0.90, the longitudinal KV2 at the temperature of-40 DEG C is larger than or equal to 198 J, the corrosion resistance index I value is larger than or equal to 6.75, the relative corrosion resistance is larger than or equal to 2