13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- Figure 1. Procedure of cutting specimens 2.2. AE measurement during tensile test AE measurements were applied with 4 channels in order to remove friction noise from jig of tensile test machine. Positions of AE sensors are shown in Fig. 2. AE sensors used in this study were M304A (Fuji ceramics, Japan). Continuous Waveform Memory (CWM), which was developed by our group, was used to perform AE measurements [7]. The high pass filter was set at 100 kHz. All AE signals are wavelet transformed in order to emphasize dependence of time and frequency. Various threshold levels were set from 60dB to 80dB with an interval of 5dB to detect signals with wide range of amplitude. Then, the data was integrated. Figure 2. AE sensors positions 2.3. EBSD test Electron Backscatter Diffraction (EBSD) analysis was performed to evaluate the texture during the tensile testing. The software used in this study was OIM-Analysis 5 of TSL Solutions. Specimens before deformed and after deformed until a strain value of 3% were cut and then polished by a machine called “Cross section Polisher” (CP), which utilizes an argon iron beam to mill the sample. This method prevents any damages from mechanical polishing and therefore the suitable surface for EBSD is easily obtained. Then, automated EBSD scans were performed in the stage control mode with TSL data acquisition software with a step size of 1.5 μm. Average grain size and Schmid factor were calculated from this result. Schmid factor used in this paper is an average value of each grain.
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