Effect of Controlled Cooling on Microstructure and Mechanical Properties of CSP Low Carbon Mn-Containing Steel

By using a thermal-simulator Gleeble 1500, CCT curves of an EAF-CSP low carbon Mn-containing steel, which had been deformed in austenite region twice, were determined. The effect of accelerated cooling conditions on the microstructure and mechanical properties of the steel was studied. The steel contains 0.17% C, 1.21% Mn and 0.28% Si (mass fraction): it was found that the Ar₃ temperature is lowed by increasing the cooling rate and results in the further grain refinement. The mixture of bainite and ferrite appears while the cooling rate reaches 20 ℃/s and over. The ratio of yield to strength could be decreased by increasing the fraction of bainite. Banding structure of ferrite/pearlite exists in the steel with finishing rolling temperature 790 ℃ and coiling at 550 ℃. Accelerating the cooling rate is an effective way to avoid band structure.