A weathering steel Cu-P-Cr-Ni-Mo has been developed which exhibits special continuous cooling transformation characteristics which permit the desired dual-phase (DP) microstructure to be obtained by direct hot-rolling. Hot-rolling procedures to obtain DP microstructures have been designed based on the continuous cooling transformation diagram of weathering steel Cu-P-Cr-Ni-Mo. The results show that the microstructures of DP weathering steels Cu-P-Cr-Ni-Mo are characterized by an irregular distribution of island-shaped martensite-austenite in the matrix of polygonal ferrite grains. DP weathering steel Cu-P-Cr-Ni-Mo with favorable corrosion resistant property, weldability and mechanical properties, such as, high strain hardening exponent values, a lower ratio of yield to tensile strength, and higher strengths; and is obtained successfully by direct hot-rolling.