High stereographic resolution texture and residual stress evaluation using time-of-flight neutron diffraction

Abstract

The division of neutron detector panel regions has improved the precision of complex texture evaluation and appropriate sample rotation enhances the texture reliability in a limited neutron beam time. The TAKUMI instrument has achieved satisfactory texture precision for a limestone standard sample. The compressive rolling direction–transverse direction in-plane stress field was quantitatively measured in martensite layers of a martensite–austenite multilayered steel, and this stress field was found to originate from the martensite transformation strain and the linear contraction misfit between austenite layers and newly transformed martensite layers.

Microstructural Features and Ductile-Brittle Transition Behavior in Hot-Rolled Lean Duplex Stainless Steels

“…The sample was two-axes (, ) rotated 35 times to collect totally 525 neutron diffraction profiles with different scattering vectors using an Euler cradle [15,16]. The obtained TOF neutron profiles (with a lattice plane spacing (d) range of 0.05~0.22 nm, including 18 diffraction peaks of γ and 15 of α) were analyzed using MAUD (Materials Analysis Using Diffraction) software [17] to reconstruct the multiphase pole figures and simultaneously to determine the globally averaged γ volume fraction [18], which has been recommended for a textured steel [15,16]. Such pole figures were further employed to quantitatively calculate multiphase ODFs.…”

“…The difference between the X and Y planes is believed to stem from the difference in the mean free length of α grain; the facet width with {100} cleavage fracture in an α grain is smaller for the X plane (i.e., the length along Y-axis: 10.3 µm for LNi as described in Section 3.1) than that for the Y plane (the length along X-axis 30.6 µm). The effective gran size for fracture unit employed for ferritic steels [16][17][18][19]32], is difficult to apply to the present steels. For the cast duplex stainless steels [10][11][12], small γ grains were dispersed within a huge α grain and hence the DBTT was summarized assuming the α grain size as the effective grain size (ignoring the presence of γ grains) in Figure 18.…”

Evaluation of Residual Stress Relaxation in a Rolled Joint by Neutron Diffraction

“…Considering that only the macro strains and the macro stresses were investigated in this paper by using the limited experimental neutron diffraction data, the effect of texture-related potential intergranular strain on the residual stress [15] was omitted here and the early classic stress model was simply employed. However, such similar pioneering researches involving in the strain, stress and texture evaluation with a little higher uncertainty have an important promotive role to develop and upgrade the neutron diffraction stress and/or texture measurement techniques in Japan using the constant wavelength neutron source at Japan Research Reactor No.3 (JRR-3, Tokai, Japan) [23][24][25][26][27] and the spallation neutron source at Japan Proton Accelerator Research Complex (J-PARC, Tokai, Japan) [28][29][30]. Actually, the rapid texture measurement technique [29] and the simultaneous measurement technique of the phase fractions, the strain, the stress and the texture [30] have been well established using the BL20 (iMATERIA) and BL19 (TAKUMI) neutron diffractometers at J-PARC, respectively, which provide us wider accessibility to neutron diffraction techniques for accelerating the research and development activities of advanced engineering materials and related products [30], together with other domestic and oversea neutron diffraction facilities, for example, the diffractometer for residual stress analysis (RESA-1) at JRR-3, Japan [31,32] and the Residual Stress Neutron Diffractometer (RSND) at the China Mianyang Research Reactor (CMRR), Beijing, China) [33].…”

Distinct Recrystallization Pathways in a Cold-Rolled Al-2%Mg Alloy Evidenced by In-Situ Neutron Diffraction

“…Given the fact that optical microscopy showed a fully recrystallized structure after annealing for 20 min at 360 • C, the in-situ isothermal annealing treatments were performed in the temperature range from 250 to 360 • C, and the annealing times from 20 to 210 min. The in-situ isochronal annealing was performed at two TOF neutron diffractometers, HIPPO and VULCAN, for two heating rates with nominal values of 2 • C/min and 7 • C/min, and in the temperature span from room temperature to 400 • C. HIPPO is a TOF instrument dedicated for texture measurements [40][41][42][43][44][45][46], while at VULCAN engineering diffractometer, the texture characterizations and the corresponding data analysis were developed as a complementary capability [47,48].…”