Thermodynamic Calculation and Experimental Study on Complex Phase Steel

摘要

Using Thermo-calc software, transformation points as well as bainite starting temperature of the CP steel studied in the present work were calculated. Based on the measured CCT curve, the steels were treated at different conditions using Gleeble-3500 thermal simulation tester. To study the effects of cooling conditions on mechanical properties and microstructure of the steels after austenization, a combination of tensile tests at room temperature, SEM and TEM techniques was applied. Results showed that effective design of chemical composition and heat treatments can be achieved using Thermo-Calc software. The CP steel with carbon equivalent of 0.43% achieved B/M complex microstructure when austenized at 975°C and followed by isothermal holding at bainitic transformation temperature of 450°C. The tensile strength is 843.29 MPa and the elongation is 14.28%.