PSI - Issue 2_A

Stijn Hertelé et al. / Procedia Structural Integrity 2 (2016) 1763–1770 Hertelé et al. / Structural Integrity Procedia 00 (2016) 000–000

1769

7

5

50

E = 200 GPa, n = 15, a / W = 0.3

40 45 50 55 60

n = 10, 15, 20

Slip line angle  (°)

45

 0 (°)

n = 10, 15, 20

 ' (°/mm)

 (°) = 47.1 + 2.6 CTOD(mm)

 0

 ’

40

0

0.0

1.0

2.0

3.0

0.2 0.3 0.4 0.5 0.6

0.2 0.3 0.4 0.5 0.6

CTOD(mm)

a / W

a / W

(a)

(b)

(c)

Fig. 6. (a) Slip line angle linearly increases as a function of CTOD. (b, c) Graphical summary of  0 and  ’ values.

Fig. 7. (a) Post mortem fractography; (b) Post mortem weld macrography; (c) CTOD-R curve measured by unloading compliance.

Figure 8(a) shows the evolution of slip line trajectories (plotted in the undeformed state) for increasing specimen deformation. It is immediately clear that the trajectories are significantly more irregular than the ones observed in the numerical study (section 3.1). Recalling from section 2.2 that numerically predicted slip lines have been experimentally validated against homogeneous SE(T) tests by Van Gerven et al. (2015), the irregularity of patterns is attributed to the presence of heterogeneous weld properties. Indeed, plotting a selection of slip lines against their corresponding positions in the weld Vickers hardness map (extract of Fig. 1) reveals that slip lines avoid regions of high hardness that occur in the weld heat-affected zones (indicated in red). In other words, slip lines tend to follow a path of weakest resistance.

Fig. 8. (a) Slip lines for various levels of increasing CTOD; (b) Selection of slip lines plotted against the HV5 map of Fig. 1.