Very strong bainite

Steel with an ultimate tensile strength of 2500 MPa, a hardness at 600-670 HV and toughness in excess of 30-40 MPa m(1/2) is the result of exciting new developments with bainite. The simple process route involved avoids rapid cooling so that residual stresses can in principle be avoided even in large pieces. The microstructure is generated at temperatures which are so low that the diffusion of iron is inconceivable during the course of the transformation to bainite. As a result, slender plates of ferrite, just 20-40 nm thick are generated, giving rise to the extraordinary properties. (c) 2004 Elsevier Ltd. All rights reserved.