Abstract：By means of DIL805A/D quenching deformation dilatometer, the influence of heat treatment process on the microstructure and properties of 960 MPa high strength steel was studied by optical microscopy (OM), transmission electron microscopy (TEM), tensile property at room temperature, and impact energy test at -40 ℃. The results showed that the content of martensite gradually increased and content of ferrite gradually decreased with the increase of quenching heating temperature in range of 790880 ℃. The content of ferrite was nearly zero and the microstructure was the most uniform and small when quenched at 850 ℃. As the tempering temperature increased from 180 ℃ to 450 ℃, the lath of martensite gradually disintegrated and the lamellar cementite began to aggregate and spheroidize. When the quenching heating temperature was higher than 850 ℃, the yield strength of the material was over 960 MPa. When tempered at 450 ℃, the material had better impact toughness. For the steel in this study, the quenching at 850 ℃ and tempering at 450 ℃ enabled the best matching of strength and toughness.
2021, Vol. 39 
