Crack Paths 2006

10-5

2'

2

-6

1'

10

1

-7

10

-8

10

-9

10

a

-10

10

b

0,9

0,8

0,7

2 '

0,6

0,5

1 '

0,4

0,3

30 60 90 1 2 0 1 5 0

KI, KIeff, M P a m 1 / 2

Figure 1. Dependencies da/dt - KI(1, 2), da/dt - KIeff(1c, 2c) and D - KI(1cc, 2cc) for

tempered at 473 K 0.2C-13Cr steel in 3 %NaCl solution (1, 1c, 1cc) and tempered at

673 K 0.45C-Cr-2Ni-Mo-V steel in distilled water (2, 2c, 2cc).

Crack branching causes a number of unexpected effects in corrosion fracture

mechanics. For example, the lifetime curve for martensitic stainless steels is non

monotonic and consists of two parts (Fig. 2a): in the lower part the crack micro- and in

the upper part macrobranching are observed.

23450

102

103

104

1

b

W , min

a

2 0

30

40

10 -7 -6 2 '

2

/ s

1 '

d a / d t , m

10-8

KI, K I e f f , M P a m 1/2

Figure 2. The life-time diagram (a) and K D F(b) in da/dt - KI coordinates (1, 2) and da/dt -

KIeffcoordinates (1c, 2c) for 0.2C-13Cr steel (tempered at 473 K) in 3 %NaCl solution at the

corrosion potential (1, 1c) and cathodic potential M = -1200 m V(2, 2c).