500 MPA GRADE LOW YIELD RATIO WEATHER-RESISTANT BRIDGE STEEL AND MANUFACTURING METHOD THEREFOR

摘要

A 500 MPa grade low yield ratio weather-resistant bridge steel and manufacturing method therefor, made up of the following components by mass percentage: 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 remainder being Fe and unavoidable impurities. By means of scientific component design and matching controlled rolling/controlled cooling + tempering manufacturing methods, the weather-resistant bridge steel is imparted with the properties of low yield ratio, extreme temperature toughness, and high ductility and malleability.