A Study of Phase Transformations in High-Chromium Ferritic-Martensitic Steels by Magnetometry

Resumo

Phase transformations in high-chromium ferritic-martensitic steels are studied using magnetometric analysis of the magnetic field. A designed, certified and experimentally tested facility for measuring the magnetic permeability of small (pea-size) specimens is described. The facility makes it possible to determine the temperatures of magnetic transformations and, in some cases, the thermal effects of phase transformations. Examples of application of the developed method for determining the characteristics mentioned are given and used to plot diagrams of isothermal transformation of supercooled austenite. An analysis of pairs “mechanical properties – parameters of diagrams of isothermal transformation” is performed, and the dependences obtained are analyzed. The formulated features of the parameters of the diagrams of isothermal decomposition may be used for developing high-chromium ferritic-martensitic steels with high refractoriness. The limits of the applicability of the developed methods and of the used facility are presented.