Issue 37

D. Angelova et alii, Frattura ed Integrità Strutturale, 30 (2017) 60-68; DOI: 10.3221/IGF-ESIS.37.08

Steel 316L , S-N Curves

Murakami,Uncharged, f=5 Hz Skipper, Uncharged, f=50 Hz Murakami, Uncharged, f=1.5 Hz Murakami, Uncharged, f=0.0015 Hz Own data, Uncharged, f=11 Hz

Murakami, Charged, f=5 Hz Skipper, Charged, f=50 Hz Murakami, Charged , f=1.5 Hz Murakami, Charged, f=0.0015 Hz

700

600

b)

500

- 0,064

σ a = 1003.9N f

300 Stress range, σ a [MPa] 400

R² = 0.9065

Group B  a = 280 MPa

- 0,081

σ a = 1044.8 N f

R² = 0.9865

- 0.1007

 a = 1139.1 N f

200

R 2 = 0.7227

Group A  a = 260 MPa

100

1000

10000

100000

1000000

10000000

100000000

Number of cycles to failure N f , [cycles]

a)

c)

Charged,Gas 3.9 ppm, f = 0.0015Hz Uncharged,2.6ppm, f= 0.0015Hz Charged,Cathodic 4.3 ppm, f= 1.5 Hz Uncharged,2.6 ppm, f = 1.5 Hz NDH - HT,0.47 ppm, f= 0.0015 Hz Group B -  a =280 MPa; Steel 316L

Group A -  a =260 MPa; Steel 316L

Charged, Cathodic 4.3 ppm, f = 5 Hz Charged, Cathodic 3.6 ppm f= 1.5 Hz

Uncharged,2.6 ppm, f = 5 Hz Uncharged,2.6 ppm, f = 1.5 Hz

1000 1200 1400 1600 1800 2000

1000 1200 1400 1600 1800 2000

Steel 316L

Crack length , 2 a [µm]

Crack length , 2 a [µm]

NDH-HT f = 0.0015 Hz

f = 0.0015 Hz

f = 1.5 Hz

f = 5 Hz

f = 1.5 Hz

0 200 400 600 800

0 200 400 600 800

0

50000

100000

150000

200000

250000

300000

0

5000

10000

15000

20000

Number of cycles, N f [cycles]

Number of cycles, N f [cycles]

d)

Steel 316L , σ a = 260 MPa

Steel 316L , σ a = 280 MPa

100

100

10

10

1

1

Murakami, Uncharged, f = 1.5 Hz Murakami, Charged, f = 1.5 Hz Murakami, Uncharged, f = 5 Hz Murakami, Charged, f = 5 Hz Skipper, Uncharged, f = 50 Hz Skipper, Charged, f = 50 Hz Own, Uncharged, f = 11 Hz

Murakami, Uncharged, f = 0.0015 Hz Murakami, Charged, f = 0.0015 Hz Murakami, Uncharged, f = 1.5 Hz Murakami, Charged, f = 1.5 Hz Skipper, Uncharged, f = 50 Hz

0.1

0.1

f, [Hz]

0.01

0.01

f, [Hz]

0.001

0.001

Skipper, Charged, f = 50 Hz Own, Uncharged, f = 11 Hz

0.0001

0.0001

1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 Number of cycles, N f [cycles]

1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 Number of cycles, N f [cycles]

e)

Steel 316L, Frequency influence tendency

100

10

1

Uncharged, σa = 260 Mpa Charged, σa = 260 Mpa Charged, σa = 280 Mpa Uncharged, σa = 280 Mpa NDH - HT, σa = 280 Mpa  P  P  P  P  P

f, [Hz]

0.1

0.01

0.001

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

Number of cycles, N f

[cycles]

f) Figure 5 : Tests: Wöhler curves, a) ; Curves a-N for Steel 304, 280MPa, b) & Steel 316L, 260MPa, c) ; Hydrogen influence on fatigue lifetimes at different frequencies, e-f) .

66