Microstructure and Mechanical Properties of Ultra-High Strength Steel Plates with High Deformability
High deformability has been considered as a critical factor of ultra-high strength steel plates subjected to compressive, tensile, and bending deformation induced by large ground movements. In this paper, various dual phase microstructures consisting of soft ferrite and strong low-temperature transformation phases without deformation in the (austenite + ferrite) two-phase temperature region after controlled rolling were introduced and then the mechanical properties were discussed with emphasis on deformability such as yield ratio and uniform elongation. Ultra-high strength steel plates fabricated by a modified thermo-mechanical control process showed lower yield ratio of under 0.75 and higher uniform elongation of 5% as a minimum, as compared to commercial API X100 and X120 grade pipeline steels, without much sacrifice of Charpy impact properties because of an appropriate formation of soft ferrite and strong low-temperature transformation phases.
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
B. C. Hwang et al., "Microstructure and Mechanical Properties of Ultra-High Strength Steel Plates with High Deformability", Materials Science Forum, Vols. 638-642, pp. 3266-3271, 2010