Low-cost 650MPa-grade high-strength steel strip and preparation method thereof

The invention discloses a low-cost 650MPa-grade high-strength steel strip and a preparation method thereof. The preparation method comprises the following steps: steel-making, continuous casting, hot rolling, acid rolling and continuous annealing; the high-strength steel strip comprises the following components in percentage by weight: 0.05-0.10 percent of C, 0.70-1.10 percent of Mn, 0.07-0.13 percent of Ti, 0.20-0.35 percent of Si, less than or equal to 0.015 percent of S, less than or equal to 0.020 percent of P and the balance of iron and inescapable impurities. According to the method, the precipitation strength of strip steel is realized by adopting the micro-alloy element Ti with low cost; the control on the strength and the plasticity of the strip steel is realized by adopting a hot-rolled low-temperature finish rolling and coiling technology; the strength of cold-rolled strip steel is improved by adopting the high cold rolling reduction ratio; the strength and the extensibility of the strip steel are ensured by adopting reasonable annealing temperature. With the adoption of the preparation method disclosed by the invention, the production cost of the high-strength steel with a yield strength reaching 650 MPa grade can be significantly reduced.