High-strength and high-plasticity dual-phase steel and manufacturing method thereof

The invention relates to high-strength and high-plasticity dual-phase steel and a manufacturing method thereof. The dual-phase steel comprises the chemical components in percentage by weight: 0.07-0.19% of C, 0.10-0.50% of Si, 1.00-2.30% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.008% of N, 0.02-0.07% of Al, less than or equal to 0.40% of Mo, less than or equal to 0.06% of Nb, and the balance of Fe and other inevitable impurities. According to the invention, by controlling the soaking temperature, slow cooling speed, slow cooling temperature, quick cooling temperature and the like of the continuous annealing process, the high-strength and high-plasticity dual-phase steel with martensite, epitaxial ferrite and residual ferritic structure can be manufactured; and continuous annealing line with a high-speed and high-hydrogen gas jet cooler is adopted, so that the content of alloy elements in the steel can be reduced, and the shaping and welding properties of steel plates can be ensured.