Method for improving mechanical properties of steel plate through thermal forming-subcritical quenching-partitioning technology

The invention relates to a method for improving the mechanical properties of a steel plate through a thermal forming-subcritical quenching-partitioning technology. According to the method for improving the mechanical properties of the steel plate through the thermal forming-subcritical quenching-partitioning technology, the steel plate is heated to a temperature over Ac3 at a certain rate, and the temperature is kept for a certain time; the steel plate is transferred into a stamping die for hot stamping forming and quenching treatment, the steel plate is quenched to a temperature (QT1) between Ms and Mf, and the temperature is kept for a certain time; the steel plate is reheated to a temperature between Ac1 and Ac3, and the temperature is slightly lower than Ac3 and kept for a certain time; then, the steel plate is rapidly quenched to a temperature (QT2) between Ms and Mf, and the temperature is kept for a certain time; then, the steel plate is reheated to a temperature slightly higher than the Ms, and the te