Toughness of Advanced High Strength Bainitic Steels
Carbide free bainite has achieved the highest strength and toughness combinations to date for bainitic steels in as-rolled conditions. By alloying designing and with the help of phase transformation theory, it was possible to improve simultaneously the strength and toughness because of the ultra-fine grain size of the bainitic ferrite plates. Ultimate tensile strengths ranging from 1600 MPa to 1800 MPa were achieved while keeping a total elongation higher than 10 %. Their toughness at room temperature matches tempered martensitic steels, known to be the best-in-class regarding this property. However, it has been observed that the presence of coalesced bainite leads to a dramatic deterioration in toughness in these novel high strength bainitic steels.
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
F. G. Caballero et al., "Toughness of Advanced High Strength Bainitic Steels", Materials Science Forum, Vols. 638-642, pp. 118-123, 2010