Magnetic and X-ray diffraction measurements for the determination of retained austenite in TRIP steels

The accurate determination of the volume fraction of retained austenite is of great importance for the optimization of transformation induced plastici ty (TRIP) steels. In this work, two aluminium-containing TRIP steels are st udied by means of magnetization and X-ray diffraction (XRD) measurements. B y fitting the field dependence of the approach to saturation in the magneti zation curves, the saturation magnetization is determined, which is linearl y related to the volume fraction of retained austenite. Moreover, informati on with respect to the microstructure can be obtained from the fitting para meters and the demagnetizing factor for the magnetization curve. The volume fractions obtained from the magnetization measurements are compared with d ata from XRD measurements. A discussion of the data suggests that magnetiza tion measurements lead to more reliable results and a more sensitive detect ion of the retained austenite than XRD measurements. (C) 2001 Elsevier Scie nce B.V. All rights reserved.