Position Dependence of SS304 and Iron Phases in Welded Specimen by Neutron Diffraction and Bragg-Edge Transmission Method KENJI IWASE, HIROTAKA SATO, KAZUHIRO MORI, TAKASHI KAMIYAMA, TORU ISHIGAKI, and YOSHIAKI KIYANAGI We investigated the nondestructive examination method by neutron scattering. A welded plate of SS304 (fcc) and iron (bcc) was investigated using neutron diffraction and the Bragg-edge transmission method. We tried to clear the positions of the welded area, SS304 phase, and iron phase and to determine the lattice spacing. The determined value of d 111 for SS304 is 2.07471(8) A ˚ using neutron diffraction. With Bragg-edge transmission, it is possible to collect the information of a specimen as two-dimensional (2-D) images using a 2-D position sensitive detector at a pulse neutron source. The determined d 111 of SS304 phase indicates between 2.0745(8) and 2.0752(9) A ˚ depending on the measurement points using Bragg-edge transmis- sion. The same tendency was also seen in iron phase. The determined d 110 of the iron phase is 2.02802(1) A ˚ using neutron diffraction. The determined d 110 of iron phase indicates between 2.0266(7) and 2.0321(13) A ˚ using Bragg-edge transmission. The determined d using diffraction exists within that of Bragg-edge transmission. In order to clarify the position dependency of the phase and lattice spacing, the combined diffraction and Bragg-edge transmission is effective. DOI: 10.1007/s11661-011-0655-6 Ó The Minerals, Metals & Materials Society and ASM International 2011 I. INTRODUCTION NEUTRON diffraction has been used as a nonde- structive examination of industrial materials, because neutrons can penetrate a bulk specimen 1000 times deeper than X-ray. Precise lattice parameter measure- ments using high-resolution diffractometers were made on the Al 2 O 3 /YAG ceramic composite [1] and a + c Fe-Cr-Ni dual-phase steels, [2] from which the lattice strain in the materials has been evaluated. Martensitic transformation in Fe-30Ni-0.23C steel was investigated by in-situ neutron diffraction between 300 K and 100 K (27 °C and –173 °C) (the M s temperature is 216 K (–57 °C)). [3] The obtained diffraction data indicate a high axial ratio of c/a = 1.0254 in freshly formed bct martensite; the decrease of c/a in tempering suggests carbon diffusion even below room temperature and remarkable diffraction peak broadening both in the newly formed martensite and the coexisting austenite due to the internal strain in the alloy. Neutron radiography has also been used as a nonde- structive examination of materials. Recently, neutron radiography using a pulsed neutron source has opened a new field; neutron transmission experiment coupled with a time-of-flight (TOF) method gives energy-dependent neutron cross section. Such measurements were carried out at the pulsed neutron source ISIS in the United Kingdom. [4,5] The total neutron cross section evaluated from the transmission spectrum exhibits a steplike decrease, the so-called Bragg edge (Figure 6 in Refer- ence 4). The Bragg edges occur, because for a given hkl reflection, the Bragg angle increases as the wavelength increases until 2h = 180 deg. At wavelengths greater than this critical value of k =2d hkl , no scattering of the hkl reflection can occur. Mizukami et al. developed a pixel-type two-dimen- sional (2-D) Li-glass position sensitive detector (PSD) [6] suitable for the transmission measurement. By using this detector behind the bulk sample, the total cross section at each sample position corresponding to each pixel position was obtained. A test experiment of transmis- sion measurement was carried out at the KENS pulsed neutron source in KEK on a welded plate of SS308 (austenite 82 pct, ferrite 18 pct) and SS304 (austenite 100 pct) to detect the welded area. [7] Thus, the Bragg- edge transmission measurement using 2-D PSD has unique advantages over conventional neutron diffrac- tion in two ways: (1) detection of total cross section of segments in the bulk sample, and (2) determination of lattice spacing of the segments from the cross-sectional spectrum. Engineering materials, vehicle engine and turbine blades, etc., have the distribution of residual strain and KENJI IWASE, Lecturer, and TORU ISHIGAKI, Professor, are with the Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Ibaraki 319-1106, Japan. Contact e-mail: fbiwase@ mx.ibaraki.ac.jp HIROTAKA SATO, Postdoctoral Student, and TAKASHI KAMIYAMA and YOSHIAKI KIYANAGI, Professors, are with the School of Engineering, Hokkaido University, Sapporo 060-8628, Japan. KAZUHIRO MORI, Assistant Professor, is with the Research Reactor Institute, Kyoto University, Osaka 590-0494, Japan Manuscript submitted September 9, 2010. Article published online March 23, 2011 2296—VOLUME 42A, AUGUST 2011 METALLURGICAL AND MATERIALS TRANSACTIONS A