PSI - Issue 37

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

544

5

a

b

Fig. 4. Specimens after fatigue tests, (a) initial condition, (b) after LSP

The rapid crack evolution is observed in the titanium specimens. The crack length was measured by potential drop method during the test. The detailed description of this method is given in [Bowler N.,]. Figure 5(a) shows the crack length during the experiment. This dependence shows that fatigue crack in the LSP treated specimen and in the initial specimen initiates after 2.5 x 10 4 cycles. After the 4 x 10 4 cycles the crack length of the LSP treated specimen rapidly increases. Figure 5(b) shows temperature evolution versus crack length. It can be seen that the LSP treated specimen has a higher heat dissipation from the beginning of the test until the fracture.

b

a

Fig. 5. The measurements of crack length in Titanium Grade 2 specimens during the fatigue test (a). Titanium Grade 2 specimen temperature evolution versus crack length during fatigue tests (b).

Figure 6 shows evolution of surface temperature for Armco-iron (a) and Titanium Grade 2 (b) specimens in the initial state and after LSP treatment during the fatigue tests. It should be noted that the curves have the same character but the LSP treated specimens heat faster than the specimens in the initial state.