Principles of Increasing the Strength and Toughness of Ferritic/Martensitic Steel Produced by Cold Rolling

Abstract

This paper presents the results of studying the evolution of the structure and mechanical properties of 12Cr–2W ferritic/martensitic steel after cold rolling and additional heat treatment. X-ray diffraction analysis, transmission electron microscopy, and electron backscattering diffraction were used to study the structure. A significant increase of tensile strength up to a tensile strength of 1380 MPa was observed after cold rolling to 50% reduction and subsequent re-quenching from the austenite region. Compared to samples subjected to standard treatment, the use of this combined treatment led to the increase of impact toughness by 22 times up to 550 kJ/m2. The principles of achieving enhanced strength and toughness by reducing the grain size and increasing the fraction of carbides and the share of coincident site lattice (CSL) boundaries are discussed.