日本原子能研究所 (JAEA) 与日本高能加速器研究所 （KEK）合作建设的高能质子加速器 (J-PARC) 项目是于2008年开始运行的世界领先的散裂中子源。随着能量选择法成像技术的研究开发，其中利用材料的透射信号变化的布拉格边效应成像法，配合最新开发的数据处理程序，使得在微观尺寸上获得结构参数的宏观二维分布得以实现，包括织构变化，相转变，相分布，残余应变等。本报告将介绍中子飞行时间法成像技术对不同钢铁材料的三点弯曲变形行为的研究结果，同时将介绍利用中子散射实验和SEM/EBSD显微结构表征对布拉格边效应成像获取的结构参数信息的验证分析。另外，将介绍布拉格边效应透过成像技术在其他工程应用中的最新结果。

Quantitative Evaluation of Microstructure in steel materials using Time-of-Flight Neutron Bragg-edge Transmission Imaging
   Time-of-flight (TOF) neutron Bragg-edge transmission (BET) imaging makes it possible to quantitatively visualize the two-dimensional distribution of microstructure within a sample.
   To study the deformation behaviors of different steel materials under non-homogeneous bending, in the present study, several kinds of bent steel plates: 1) a ferrite single-phase steel, 2) an austenite single-phase steel, 3) a hot-rolled duplex stainless steel, and 4) a metastable austenitic steel for stress-induced martensite transformation, were characterized by TOF Bragg-edge transmission imaging. Pulsed neutron transmission imaging experiments were performed at BL10 NOBORU and BL22 RADEN of the MLF/J-PARC. using a Gas Electron Multiplier (GEM) two-dimensional (2D) detector. The measured Bragg-edge spectra were analyzed by RITS (Rietveld Imaging of Transmission Spectra) code. Quantitative 2D mappings of crystallographic texture, crystallite size and phase distribution were successfully provided by non-destructive transmission technique. The obtained BET imaging results were also compared with those using the neutron diffraction experiment method and optical microstructure observations. The microstructure evolution caused by bending deformation in all samples, especially non-homogeneous martensite transformation in austenitic steel, will be presented.
   In addition, some other examples of BET imaging for engineering application will be introduced.