PSI - Issue 6

S.A. Atroshenko et al. / Procedia Structural Integrity 6 (2017) 190–195 Author name / Structural Integrity Procedia 00 (2017) 000 – 000

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holder was manufactured. It provided possibility to test two semicircle samples side by side simultaneously (see figure 2).

Fig. 2. Holder with 2 mounted samples.

An optical microscope Axio-Observer Z1-M was used in a dark field mode to examine fracture patterns. The viscous fracture regions are characterized by a dull gray appearance with characteristic "fibers". The brittle fracture pattren is crystalline, with no visible traces of plastic deformation on the fracture surface. The amount of viscous component on the fracture surface, shear percentage, was determined by the formula shear percentage = 100-X, where X is the fraction of the brittle component in the considered fracture surface area. Percentage of brittle fracture component was determined visually from the microscopic image. The damaged layers were studied from properly prepared cross sections of the samples. In order to measure material mass loss due to erosion, the samples were weighted before and after tests and mass difference was registered. Roughness of the working surfaces of the samples was investigated using perthometer.

3. Results and discussions

Figures 3 and 4 depict sample mass loss and sample surface roughness (Ra) after erosion tests. The figures contain data on the alloy in initial coarse-grained state (marked as Ti-6Al-4V) and data for the HPT and ECAP processed specimens. One should note here, that in all descriptions of the figures air flow velocities are mentioned. Actual velocities of the abrasive particles, which depend on the powder dimensions, can be found in table 1.