PSI - Issue 7

Z.H. Jiao et al. / Procedia Structural Integrity 7 (2017) 124–132

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Z.H. Jiao et Al./ Structural Integrity Procedia 00 (2017) 000–000

forging alloy and basically consistent with 2# forging alloy. Similar to RT, the SLM alloy exhibits higher FCGR than forging alloy in the lower △ K region. In conclusion, the FCG resistance of SLM produced Ti6Al4V is comparable to conventional process alloys concerned in this study.

Table 3 Paris equation parameters for FCGR of SLM produced Ti6Al4V specimens.

Temperature ( ℃ )

Stress ratio

C

m

2.90 2.98 2.23 2.12

0.1 0.5 0.1 0.5

2.99×10 -8 3.16×10 -8 2.55×10 -7 3.85×10 -7

RT

400 ℃

10 -2

(a)

(b)

Ti6Al4V(SLM) RT R =0.1

Ti6Al4V(SLM) 400 ° C R =0.1

10 -3

R =0.5

R =0.5

XY YZ ZX

XY YZ ZX

XY YZ ZX

XY YZ ZX

10 -3

10 -4 d a /d N , mm/cycle

10 -4 d a /d N , mm/cycle

10 -5

5 6 7 8 910

20 30 40 50 60 7080

5

10

15 20 25 30 35 40 4550

∆ K , MPa√m

∆ K , MPa√m

10 -2

(c)

(d)

Ti6Al4V(SLM) R =0.1 RT

10 -3

Ti6Al4V(SLM) R =0.5 RT

400 ° C

400 ° C

XY YZ ZX

XY YZ ZX

XY YZ ZX

XY YZ ZX

10 -3

10 -4

d a /d N , mm/cycle

10 -4 d a /d N , mm/cycle

10 -5

10 -5

5 6 7 8 910 Fig. 5. The d a /d N - △ K curves of SLM produced Ti6Al4V specimens under different conditions. (a) RT; (b) 400℃; (c) R =0.1; (d) R =0.5. 10 -2 (a) 10 -2 20 30 40 50 60 7080 ∆ K , MPa√m 15 20 25 30 35 40 ∆ K , MPa√m 5 10

(b)

Ti6Al4V R =0.1 400 ℃

Ti6Al4V R =0.1 RT

XY(SLM) YZ(SLM) ZX(SLM) bar 1#forging 2#forging

XY(SLM) YZ(SLM) ZX(SLM) bar 1#forging 2#forging casting

10 -3

10 -3

10 -4 d a /d N , mm/cycle

10 -4 d a /d N , mm/cycle

10 -5

10 -5

4 5 6 7 8 910 20 30 40 50 60 7080 Fig. 6. The d a /d N - △ K curves of SLM and conventionally manufactured Ti6Al4V specimens under the stress ratio of 0.1. (a) RT; (b) 400℃ . ∆ K , MPa√m 5 6 7 8 910 20 30 40 50 60 7080 ∆ K , MPa√m