Quenching-partitioning-tempering(Q-P-T)process were applied to a quenched carbide-free bainite/martensite(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 be increased greatly to 90min or even longer.The tensile strength,elongation and product of strength and elongation(PSE)of the experimental steel can achieve 1 650MPa,about 20%and over 33GPa·%,respectively.The significant increase of partitioning time and excellent mechanical properties could be related to the CFB microstructure introduced in the quenching process during the Q-P-T treatment.
