Preparation method of 980MPa-grade ultra-high-ductility cold-rolled high-strength steel

The invention relates to a preparation method of 980MPa-grade ultra-high-ductility cold-rolled high-strength steel. The method is characterized in that by regulating and controlling the initial structure of a cold-rolled annealed steel plate, 1000 MPa ultra-high-ductility cold-rolled strip steel with different yield strengths is prepared; and the specific process route comprises the steps of a cold-rolled plate is subjected to heat preservation for 80-300 s at different critical zone temperatures and then is quickly quenched to a room temperature; then the cold-rolled plate is heated again to a certain temperature between AC1 and AC3 and annealed for 80-360 s; and the cold-rolled plate is aged for 300-600 s at the temperature of 360-420 DEG C and is cooled to the room temperature to obtain a cold-rolled strip steel with the tensile strength larger than or equal to 980 MPa, the yield strength ranging from 500 MPa to 800 MPa and the product of strength and ductility being 30 GPa % or above. According to the met