Q-and-PB (quenching and partitioning in bainite zone) heat treatment process for preparing 30 GPa%-grade complex-phase steel

The invention discloses a Q-and-PB (quenching and partitioning in bainite zone) heat treatment process for preparing 30 GPa%-grade complex-phase steel, and belongs to the field of metal heat treatment. In the method, a chill plate made from low-carbon silicon-manganese-series ingredient steel is used as a raw material. The Q-and-PB heat treatment method comprises the following steps of: firstly, heating the steel plate to a temperature of greater than Ac3 and insulating heat for 2 minutes, and quenching to a temperature T1 which is between Ms and Mf; secondly, placing a test sample in a place at a temperature T2 which is greater than the temperature Ms and insulating heat for 30-600 seconds; and finally, quenching to a room temperature. Experiments prove that the low-carbon silicon-manganese-series steel prepared by the method disclosed by the invention is extremely high in strength and elongation, and the product of strength and elongation of the low-carbon silicon-manganese-series steel achieves more than 30 GPa%.