PSI - Issue 68

6

S. Ghosh et al. / Procedia Structural Integrity 68 (2025) 1329–1336 S. Ghosh et al. / Structural Integrity Procedia 00 (2025) 000–000

1334

to the combined effect of austenite and bainite and, hence, a greater retardation in crack propagation was observed (Figure 2b).

300

1000 1200 1400

(a)

(b)

250

200

0 200 400 600 800

150

100

50

0 ()*+,* .+&/0,* 1234 /,14 (µ') 0 20

40 ∆",$%& '

40 ∆",$%& '

80 $232023,* .+&/0,* 1234 /,14 (µ') 0 20

60

60

80

Fig. 3: Evolution of cyclic plastic zone (a) and monotonic plastic zone (b) with increase in ∆ in H-Si and M-Si DQP steel

(a)

(b)

Decreasing ΔK Increasing ΔK

Decreasing ΔK Increasing ΔK

100 µm

3 0 µm

(c)

(d)

Striations

Striations

1 µm

1 µm

Fig. 4. Fractography of the fracture surfaces of the CT specimens after FCGR experiment. (a,b) junction between increasing and decreasing ΔK and (c,d) presence of striations at high ΔK regions.