Method for producing high-strength steel with yield strength of 700 MPa based on short process and low cost

The invention discloses a method for producing high-strength steel with yield strength of 700MPa based on short process and low cost, and relates to the technical field of hot-rolled high-strength steel production. The method comprises the following steps: (1) smelting and continuously casting materials into a plate blank; (2) heating and descaling a continuous casting sheet billet; (3) finish rolling and water cooling; (4) coiling by a strip steel coiling machine; and (5) the cooled steel coil is subjected to cover annealing. The grain size of the produced high-strength steel with the yield strength of 700 MPa grade is 11-13 grade, the metallographic structure is ferrite and a small amount of low-carbon bainite, the yield strength ReH of a finished product with the thickness of 1.2-8.0 mm is larger than or equal to 700 MPa, the tensile strength Rm is larger than or equal to 785 MPa, the percentage elongation after fracture is larger than or equal to 18%, and a 180-degree cold bending test shows that d = a is