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 journalArticlepeer-review

4 Citations (Scopus)

Abstract

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
Volume59
Issue number7
DOIs
Publication statusPublished - 2018

Keywords

  • 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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