PSI - Issue 13

Wenbo Sun et al. / Procedia Structural Integrity 13 (2018) 1020–1025 Author name / Structural Integrity Procedia 00 (2018) 000–000

1023

4

45

40

35

30

25 a (mm)

20

a-N-0° a-N-45° a-N-00°

15

10

0

200000

400000

600000

800000 1000000

N (cycle) Figure 4. The - a N curves of SLM Titanium alloy with different building directions

Table 1. Details about specimens with different building directions

Building Direction

0°

45°

90°

Cycle at 5mm visible crack Fatigue crack growth life

430000 643600

680000 939384

410000 629068

Seven-point incremental polynomial technique was used, and fatigue crack growth rate da dN K   curves of all samples were obtained. Fatigue crack growth rates were compared with that obtained by some other scholars, shown in Fig. 5. The da dN K   curves in this paper are parallel to the Jiao’s test (2017), but the value is lower than that in Ref (2017,1996). According to our results, there is some fluctuation in the low K  regime (about 10-16 MPa m ). With the crack propagating, FCGR curves of 0° and 90° specimen are close, and the curve is slightly higher than that of 45° specimen. As a result, the fatigue crack growth rate of 45 ° specimen is slower than that of 0° and 90° specimens.

1E-6

1E-7 da/dN ( m /cycle)

0° 45° 90°

Khalil's test(RF.16) Jiao's test-0°(RF.15)

1E-8

10

20

30

40 50 60 70

Δ K ( MPa ꞏ m 0.5 ) Figure 5. da dN K   curves