Determination approach of dislocation density and crystallite size using a convolutional multiple whole profile software

Kodai Murasawa, Masato Takamura, Masayoshi Kumagai, Yoshimasa Ikeda, Hiroshi Suzuki, Yoshie Otake, Takayuki Hama, Shinsuke Suzuki

    Research output: Contribution to journalArticle

    2 Citations (Scopus)


    Neutron diffraction profile analysis using the whole profile fitting method is useful for obtaining microscopic information on metallic materials. To determine an appropriate fitting approach for obtaining reasonable and non-arbitrary results, we applied diffraction line profile analyses using the Convolutional Multiple Whole Profile (CMWP) method to diffraction patterns obtained using the Engineering Materials Diffractometer (TAKUMI, BL19) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The tensile specimens of 780MPa grade bainitic steel were uniaxially stretched until the plastic strain reached a value of 0.05. We performed CMWP analyses on the obtained diffraction patterns during tensile test with various initial parameters of dislocation density and crystallite size. These parameters were optimized in the fitting procedures to minimize the weighted sums of squared residuals (WSSRs). Following this approach, we found that unsuitable initial parameter values resulted in unreasonable convergence. Therefore, initial fitting parameters should be chosen to ensure that the initial profiles are as broad as possible. Reasonable results were obtained following this suggestive approach even when the strain anisotropy parameter is set to arbitrary values.

    Original languageEnglish
    Pages (from-to)1135-1141
    Number of pages7
    JournalMaterials Transactions
    Issue number7
    Publication statusPublished - 2018 Jan 1


    • 780-MPa grade bainitic steel
    • Crystallite size
    • Dislocation density
    • Line profile analysis
    • Neutron diffraction
    • Whole profile fitting

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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