High-strength thick hot-rolled steel sheet having excellent elongation and method for manufacturing same

Abstract

Provided are a high-strength thick hot-rolled steel sheet having excellent elongation and a method for manufacturing same. The high-strength thick hot-rolled steel sheet comprises, by weight %: 0.05-0.15% of C; 0.01-1.0% of Si; 1.0-2.0% of Mn; 0.01-0.1% of Sol. Al; 0.005-1.0% of Cr; 0.001-0.02% of P; 0.001-0.01% of S; 0.001-0.01% of N; 0.005-0.07% of Nb; 0.005-0.11% of Ti; and the remainder of Fe and unavoidable impurities, satisfies relation 1, and has a microstructure comprising, by area %: 25-50% of polygonal ferrite; 30-50% of bainitic ferrite and acicular ferrite; 20% or less of bainite; less than 5% of the sum of area fractions of carbide and pearlite structures having a diameter of 0.5 μm or more, observed within a unit area (1 cm); and less than 5% of phase MA (martensitic-austenitic constituents).