Issue 35

X.C. Arnoult et alii, Frattura ed Integrità Strutturale, 35 (2016) 509-522; DOI: 10.3221/IGF-ESIS.35.57

shown that delamination cracks may have positive effect on the impact toughness properties if their number is relatively low. Fracture surface of specimens from plate of HSLA steels which underwent a tempering step [6] and were tested at room temperature did not display any delamination cracks, unlike those tested at -30°C (cf. Table 2 and Figure 5).

Tempering Temperature, °C

CVN Impact Energy, J

Delamination cracks

As-rolled

56 60 50 51 47 45 49 50 53 49 55

No No No

200 300 400 500 550 575 600 625 650 700

Small and Local Large and Global Large and Global Large and Global Large and Global Large and Global Large and Global

Small and Local Table 2 : Charpy Impact Toughness of tempered specimens and tested at -30°C [6].

Figure 5 : SEM picture of fracture surface of Charpy specimens tempered at 200°C a) , 400°C b) , 500°C c) , 600°C d) and tested at - 30°C.

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