Influence of Cooling Rate on the Microstructures and Properties of Q550
A Q550 high strength steel was selected at two different cooling rates through ultra-fast cooling process, and its microstructures and strengthening mechanisms were analyzed. The results show the bainite transformation temperature of the steel decreased with the increasing of cooling rate.The ultra-fast cooling process can improve the performance of Q550 compared with the conventional cooling process, and the yield strength, tensile strength and elongation are 600MPa, 755MPa and 19%, and - 20 °Cimpact energy is 253J, and good strength and toughness are obtained under ultra-fast cooling process. The microstructure of this steel is bainite and good strength and toughness are caused by the refinement of bainite and fine precipitates. Ultra-fast cooling technology improves the strength and toughness of this steel effectively.
Huixuan Zhang, Ye Han, Fuxiao Chen and Jiuba Wen
F. Li et al., "Influence of Cooling Rate on the Microstructures and Properties of Q550", Applied Mechanics and Materials, Vols. 117-119, pp. 1705-1707, 2012