Effects of Different Heat Treatment Process on Mechanical Properties and Microstructure of Q690 Steel Plate

Taking high strength steel Q690 as the research object, the mechanical properties, microstructure and XRD of Q690 steel plate after treated by different processes are studied. The result shows that the mechanical properties of the Q-P-T heat treatment process have been greatly improved, the yield strength is 1112.5MPa, the tensile strength is 1285.9MPa, the elongation is 8.23%, and the surface hardness is about 39HRC. The strengthening and toughening mechanism of Q690 steel after Q-P-T process is discussed. Studies found that the good comprehensive mechanical properties of Q-P-T steel are made up of martensite, retained austenite and dispersed carbide, which are of great significance to improve the strength of the steel. (paper)