Low-yield-ratio 1030MPa-grade high-strength QP steel and production method thereof

The invention provides a 1030MPa-grade high-strength Qamp with a low yield ratio. The invention discloses P steel and a production process thereof. The thick plate comprises the following chemical components in percentage by mass: 0.15%-0.17% of C, 0.4%-0.6% of Si, 1.4%-2.6% of Mn, 0.4%-0.8% of Cr, 1.2%-1.6% of Ni, 0.2%-0.6% of Mo, 0.02%-0.08% of Nb, 0.02%-0.08% of V, 0.01%-0.03% of Ti, 0.01%-0.05% of Al, 0.8%-1.5% of Cu and the balance of Fe and inevitable impurities. According to the production process, on the basis of adopting the components, controlled rolling and controlled cooling and off-line salt bath Qamp are adopted; and P, a heat treatment process is conducted, and the 1030 MPa-grade high-strength steel with the thickness of 15 mm and the low yield ratio is prepared. Two-stage rolling is adopted in the controlled rolling and controlled cooling process, water cooling is conducted to 400-420 DEG C after rolling, and then air cooling is conducted to the room temperature. A salt bath two-step method Qa