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High stereographic resolution texture and residual stress evaluation using time‐of‐flight neutron diffraction
Author(s) -
Xu Pingguang,
Harjo Stefanus,
Ojima Mayumi,
Suzuki Hiroshi,
Ito Takayoshi,
Gong Wu,
Vogel Sven C.,
Inoue Junya,
Tomota Yo,
Aizawa Kazuya,
Akita Koichi
Publication year - 2018
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576718004004
Subject(s) - neutron diffraction , materials science , texture (cosmology) , residual stress , neutron , pole figure , austenite , rietveld refinement , stress (linguistics) , crystallography , optics , composite material , nuclear physics , diffraction , physics , microstructure , chemistry , computer science , philosophy , image (mathematics) , artificial intelligence , linguistics
Neutron diffraction texture measurements provide bulk averaged textures with excellent grain orientation statistics, even for large‐grained materials, owing to the probed volume being of the order of 1 cm 3 . Furthermore, crystallographic parameters and other valuable microstructure information such as phase fraction, coherent crystallite size, root‐mean‐square microstrain, macroscopic or intergranular strain and stress, etc. can be derived from neutron diffractograms. A procedure for combined high stereographic resolution texture and residual stress evaluation was established on the pulsed‐neutron‐source‐based engineering materials diffractometer TAKUMI at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Center, through division of the neutron detector panel regions. Pole figure evaluation of a limestone standard sample with a well known texture suggested that the precision obtained for texture measurement is comparable to that of the established neutron beamlines utilized for texture measurement, such as the HIPPO diffractometer at the Los Alamos Neutron Science Center (New Mexico, USA) and the D20 angle‐dispersive neutron diffractometer at the Institut Laue–Langevin (Grenoble, France). A high‐strength martensite–austenite multilayered steel was employed for further verification of the reliability of simultaneous Rietveld analysis of multiphase textures and macro stress tensors. By using a texture‐weighted geometric mean micromechanical (BulkPathGEO) model, a macro stress tensor analysis with a plane stress assumption showed a rolling direction–transverse direction (RD–TD) in‐plane compressive stress (about −330 MPa) in the martensite layers and an RD–TD in‐plane tensile stress (about 320 MPa) in the austenite layers. The phase stress partitioning was ascribed mainly to the additive effect of the volume expansion during martensite transformation and the linear contraction misfit between austenite layers and newly transformed martensite layers during the water quenching process.