Abstract: A micro-molybdenum-type weathering bridge steel plate disclosed by the present invention is characterized in that the steel plate is smelted from the following components by weight: C: 0.05-0.08%, Si: 0.30-0.50%, Mn: 1.25-1.35%, P: 0.010-0.014%, S?0.003%, Nb: 0.020-0.030%, Ti: 0.010-0.020%, V: 0.040-0.050%, Cu: 0.25-0.40%, Ni: 0.25-0.35%, Cr: 0.45-0.55%, Mo: 0.03-0.08%, Alt: 0.020-0.040%, and the balance from Fe and impurities. Less content of molybdenum reduces the production cost of the steel plate, the yield strength of the steel plate is 500-600 MPa, the yield strength ratio is ?0.85, and the maximum thickness of the steel plate can reach 80 mm.

Abstract: Disclosed is 500-MPa low-yield-ratio weather-resistant bridge steel and a manufacturing method therefor; the weather-resistant bridge steel includes the following components in percentage by mass: C: 0.04%-0.09%, Si: 0.15%-0.30%, Mn: 1.40%-1.50%, P: 0.009%-0.015%, S: ?0.002%, Nb: 0.020%-0.050%, Ti: 0.010%-0.020%, V: 0.010%-0.030%, Cu: 0.30%-0.40%, Ni: 0.30%-0.45%, Cr: 0.45%-0.60%, Mo: 0.08%-0.15%, Alt: 0.02%-0.04%, and the balance Fe and inevitable impurities; through scientific component designing and a matched manufacturing method combining controlled rolling and cooling and tempering, the weather-resistant bridge steel has a low yield ratio, high low-temperature toughness and high elongation.