Effect of Intercritical Temperature on the Microstructure and Mechanical Properties of 10CrMnMoSi Dual-phase Steel

This study investigated the microstructure and mechanical properties (tensile and hardness) of a 10CrMnMoSi dual-phase steel under different quenching temperatures. At intercritical temperature range (730-830 °C), martensite forms in the ferritic matrix. With the temperature increasing from 730 to 850 °C, long island martensite turns to lath martensite, and ferrite coexists in a fibrous form. In addition, the fraction of martensite increased from 10.29 to 61.22% when the temperature increased from 730 to 850 °C. The grain size of ferrite increased from 14.20 is reduced to 2.72 µm, and the martensite size is reduced from 5.35 to 2.11 µm. As the quenching temperature increases, the yield strength and tensile strength increases with a subsequent decrease in elongation. In this study, the Hollomon stress–strain model, modified Crussard-Jaoult (C-J) analysis was used to analyze the work-hardening behavior of the experimental dual-phase steel. The values of m1, m2, and n1, n2 of the samples after quenching from 790 °C are the largest, which means the deformation mechanism of the dual-phase steel begins to change at this temperature. With the temperature increases, the tensile fracture morphology changes from the ductile fracture turn to brittle fracture.