Nuclear Engineering and Design 235 (2005) 713–725 Measurement of plastic strain of polycrystalline material by electron backscatter diffraction Masayuki Kamaya a,∗ , Angus J. Wilkinson b , John M. Titchmarsh b a Institute of Nuclear Safety System, Inc. 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205, Japan b Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK Received 7 July 2004; received in revised form 5 October 2004; accepted 4 November 2004 Abstract It is important to know the degree of plastic strain in order to evaluate the susceptibility and crack growth rate of stress corrosion cracking (SCC) in stainless steel and nickel based alloy, because SCC is enhanced by the cold work and causes many problems in nuclear power plant components. In this study, electron backscatter diffraction in conjunction with scanning electron microscopy is applied to measure the plastic strain imposed to stainless steel by tensile load. A new parameter, which quantifies the spread of the crystal orientation within individual grains arising due to dislocation accumulation during plastic deformation, is correlated with imposed plastic strain. The new parameter is called ‘crystal deformation’ and is determined from the spread in misorientation from the central grain orientation. It is confirmed that this parameter has a good correlation with plastic strain and is not affected by the data density of the crystal orientation map. The dislocation density distribution is also evaluated from the misorientation from the central orientation. Relatively high dislocation density was observed near grain boundaries and grain boundary triple points, which was consistent with the observed deterioration of EBSD pattern quality in those locations. © 2004 Elsevier B.V. All rights reserved. 1. Introduction Plastic strain (cold work) imposed on materials by a shape forming process or surface grinding in manufac- turing and service often causes problems by enhancing the susceptibility to stress corrosion cracking (SCC) in stainless steel and nickel based alloys used in nu- ∗ Corresponding author. Tel.: +81 770379114; fax: +81 770372009. E-mail address: kamaya@inss.co.jp (M. Kamaya). clear power plants (Okamura et al., 2003). Recently, researches have revealed the relationship between the degree of the plastic strain and stress corrosion crack growth rate (Castano et al., 2003; Shoji et al., 2003; Magdowski et al., 1997; Vaillant et al., 1997; Speidel and Magdowski, 2000). By using these data we can pre- dict crack growth behavior and improve estimates of the time to crack penetration in order to improve struc- tural integrity assessments of components. However, it is not easy to know the degree of plastic strain for ma- terials in operating plant components. In many cases, 0029-5493/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nucengdes.2004.11.006