PSI - Issue 23

Yoshikazu Nakai et al. / Procedia Structural Integrity 23 (2019) 83–88

85

Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1 Principle of DCT.

Fig. 2 Rotation of sample.

Misorientation of the diffraction plane Sp read of rotation angle which satisfies the Bragg’s diffraction condition, Δω diff , reflects the curvature of a crystallographic plane, i.e., excessive dislocation density, and the total misorientation, β, of the plane is given by the following equation, where nomenclature is indicated in Fig. 2. diff sin   (1) where, ϕ is the angle between the normal of the diffraction plane and the rotation axes, given by   1 cos cos cos      (2) Therefore, the total misorientation, β, of each crystallographic plane can be evaluated from the rotation angle spread for the diffraction condition, Δω diff , the diffraction angle, θ, and the angle between the diffraction plane and the rotation axis, ψ, as defined in Fig. 1. The material used in the present study was an extruded AZ31 magnesium alloy with a composition (in mass %) of 2.7Al, 0.79Zn, 0.44Mn, 0.0012Fe, 0.009Ni, 0.011Cu, 0.004Si, and balance Mg. The average grain size of the alloy is 52 μm and the tensile and compressive yield strengths are 147 and 79 MPa, respectively as shown in Fig. 3. The specimens were cut by wire electric discharge machining from an extruded plate so that the longitudinal direction of the specimen coincided with the direction of extrusion. In-situ loading devices for DCT are shown in Fig. 4, where two cameras were employed for DCT and refraction 3. Material and experimental procedures

Fig. 3. Stress-displacement curves under monotonic loading.

Fig. 4. Loading device for in-situ measurement.