Measurement of microstructure changes in 9Cr–1Mo and 2.25Cr–1Mo steels using an electromagnetic sensor

Abstract

(2012) Measurement of microstructure changes in 9Cr-1Mo and 2.25Cr-1Mo steels using an electromagnetic sensor. Scripta Materialia, Volume 66 (Number 6). pp. 367-370. ISSN 1359-6462 Permanent WRAP url: http://wrap.warwick.ac.uk/67570 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.For more information, please contact the WRAP Team at: publications@warwick.ac.uk

Measured and modelled low field relative permeability for dual phase steels at high temperature

“…The high temperature EM sensor was used to measure the inductance of the pure iron and C- values and measured inductance values. The fitting method is described in [12]. The model predicted an applied magnetic field of 26 A/m at the sample position, which agrees well with the measured field (measured using a Gauss meter).…”

Magnetic Evaluation of Microstructure Changes in 9Cr-1Mo and 2.25Cr-1Mo Steels Using Electromagnetic Sensors

“…The electrical resistivity measurements for all the samples are given in Table 4 (reproduced from [31]). The tempering heat treatment resulted in a 7.49 % resistivity drop compared to the as-normalized P9 value.…”

“…Close fits between the modeled and measured real inductance for all the samples have been achieved as shown in Figure 12. The fitted relative permeability values are presented in Table 4 as well as plotted as a function of low frequency inductance values in Figure 13 (reproduced from [31]). Figure 13 indicates that the relative permeability values exponentially increase with corresponding low frequency inductance for both P9 and T22 steels in the different heat treated conditions, for this sensor design.…”

“…The EM sensor measurements of the T22 samples in terms of the real part of mutual inductance as a function of frequency, is shown in Figure 12(b) (reproduced from [31]). The L 0 value for T22 changes on tempering and after service exposure in a similar manner as for P9 although to a lesser extent.…”

“…The theory as to how the relative permeability and resistivity of a sample affect the multi-frequency EM response, for any sensor geometry, is presented elsewhere [30]. It has been shown that the multi-frequency EM sensors are able to detect the initial relative permeability and resistivity changes, resulting from microstructural changes in power plant steels during service at high temperatures [31]. However, the role of different microstructural feature changes was not considered in detail before.…”