PSI - Issue 37

A. Prokhorov et al. / Procedia Structural Integrity 37 (2022) 540–546 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Geometry of the armco-iron specimen.

Armco-iron specimens were tested by servo-hydraulic testing machine BISS Bi-00-100. The loading frequency was 10 Hz. The applied load was 125 MPa and the stress ratio was -1 for each specimen. Two series of the specimens were prepared for the tests. The first one was in the initial state. In the second series, each side of a flat part was treated by LSP [Muñoz Ja. A., Higuera O. F., Cabrera J. M.]. The LSP process was carried out at Helmholtz-Zentrum Hereon using a Q-switched Nd:YAG laser operating at 5 J energy pulse, with a spot size of 2.5 mm (square spot) and a 50% overlap. The duration of the pulse was 20 ns (full width at half maximum). 2.2. Titanium Grade 2 The geometry of Grade 2 titanium specimen is shows in figure 2. Specimens were also tested in the initial state and peened states. Specimens have a one-sided notch in the middle. It is important to initiate the fatigue crack in this area.

Fig. 2. Geometry of Ti-grade2 specimen.

The Titanium Grade 2 specimens were tested by servo-hydraulic testing machine BISS Bi-00-100. The loading frequency was 10 Hz. The applied load was 100 MPa and the stress ratio was 0.1 for each specimen. The LSP treated area is located at the distance of 1.5 mm from the notch tip and has a 21x10 mm dimensions on both sides of the specimen. Laser shock peening was carried out at the ICMM UB RAS using Q-switched Nd:YAG laser operating at 3 J energy pulse, with a spot size of 1 mm (square spot) and a 50% overlap. The duration of the pulse was 20 ns. 2.3. Residual stress The results of residual stress measurements in Armco-iron and Titanium Grade 2 are shown in figure 3(a) and figure 3(b) respectively. Residual stresses were measured using incremental hole drilling method. This technique has been described in detail in [Steinzig, M. and Ponslet, E.]. The specimen surface was covered with a steel foil before LSP-treatment. The metal foil on the surface of the specimen is used to protect the surface from increase of the roughness.