Quenching partitioning tempering （QP-T） process were applied to a quenched carbide-free bainite/mar- tensite （CFB/M） multiphase steel 40Mn2Si2Cr and its effect on the mechanical properties was studied. The results showed that the partitioning time of Q P T treatment can he increased greatly to 90 min or even longer. The tensile strength, elongation and product of strength and elongation （PSE） of the experimental steel can achieve 1650 MPa, about 20% and over 33 GPa ·%, respectively. The significant increase of partitioning time and excellent mechanical properties could be related to the CFB microstrueture introduced in the quenching process during the Q-P-T treat- ment.
