Welded high-strength steel structures and methods of manufacturing the same

摘要

The present invention is a welded high-strength steel structure having a TS of not less than 900 MPa and excellent low-temperature toughness and a method of manufacturing the steel structure. The base steel is formed of a mixed structure of martensite and lower bainite and has a TS of not less than 900 MPa, and the weld metal is steel which has the following elements based on % by weight: C: 0.01% to 0,15%; Si: 0.02% to 0.6%; Mn: 0.6% to 3%; A1: 0.004% to 0.08%; Ti: 0.003% to 0.03%; O (oxygen): not greater than 0.06%; B: 0.0002% to 0.00%; and as optional components, Cu, Ni, Cr, Mo, V, and Nb and which satisfies the following two equations: 0.25