A Non-quenched and Tempered Bainitic Steel with High Strength-Toughness and Hardenability

A non-quenched and tempered bainitic steel with high strength-toughness and hardenability had been developed.The microstructure,mechanical properties and continuous cooling transformation (CCT) curves of the steel were studied,and its strength-toughness was compared with that of the 42CrMo steel.The results show that both the tested steels microstructure cooled at air and sand after forging was bainite and the strength-toughness was similar.The steel had good hardenalility and broad bainitic transformation.The ferrite did not appear as the cooling rate was lower than 0.05℃·s-1.The mechanical properties of the bainitic steel were better than those of traditional quenched and tempered steel 42CrMo after tempered at 350℃ for 2 h.