PSI - Issue 14
S. Vishnuvardhan et al. / Procedia Structural Integrity 14 (2019) 482–490 S. Vishnuvardhan / Structural Integrity Procedia 00 (2018) 000–000
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typical da/dN vs. ∆ K curves for the specimens tested under 3.5% NaCl aqueous environment. Using the da/dN vs. ∆ K plots, best fit curves following power law in the form of Paris’ equation were obtained. Table 4 gives the fatigue crack growth constants obtained for SA 333 Gr. 6 and SA 516 Gr. 70 steels under demineralised water environment.
a
b
75
50
Frequency: 0.50
S3/CFCG8-4DW S5/CFCG8-3DW
S3/CFCG8-1AC S3/CFCG8-2AC
60
40
45
30
Current: 0.3 A
30
20
Crack length, mm
Crack length, mm
15
10
Current: 0.2 A
0
0
10000
100000
1000000
10000
100000
1000000
No. of cycles
No. of cycles
c
50
Frequency: 0.25
S5/CFCG8-1AC S5/CFCG8-2AC
40
30
Current: 0.3 A
20
Crack length, mm
10
Current: 0.2 A
0
10000
100000
1000000
No. of cycles
Fig. 4. Crack length vs. number of cycles curves. (a) SA 333 Gr. 6 and SA 516 Gr. 70 steel specimens under demineralised water environment; (b) SA 333 Gr. 6 steel specimens under 3.5% NaCl aqueous environment; (c) SA 516 Gr. 70 steel specimens under 3.5% NaCl aqueous environment
a
b
1.0E-02
1.0E-02
S3/CFCG8-4DW
S5/CFCG8-3DW
1.0E-03
1.0E-03
1.0E-04
1.0E-04
da / dN , mm/cycle
da / dN , mm/cycle
1.0E-05
1.0E-05
1.0E-06
1.0E-06
1
10
100
1000
1
10
100
1000
K , MPa m
K , MPa m
Fig. 5. Crack growth rate vs. stress intensity factor range curves for the specimens tested under demineralised water environment. (a) SA 333 Gr. 6 steel; (b) SA 516 Gr. 70 steel.
a
b
1.0E-02
1.0E-02
Frequency: 0.25
Frequency: 0.50
S3/CFCG8-1AC S3/CFCG8-2AC
S5/CFCG8-1AC S5/CFCG8-2AC
1.0E-03
1.0E-03
1.0E-04
1.0E-04
da / dN , mm/cycle
da / dN , mm/cycle
1.0E-05
1.0E-05
1.0E-06
1.0E-06
1
10
100
1000
1
10
100
1000
K , MPa m
K , MPa m
Fig. 6. Crack growth rate vs. stress intensity factor range curves for the specimens tested under 3.5% NaCl aqueous environment. (a) SA 333 Gr. 6 steel; (b) SA 516 Gr. 70 steel.
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