Issue 46

I. Čamagić et alii, Frattura ed Integrità Strutturale, 46 (2018) 371-382; DOI: 10.3221/IGF-ESIS.46.34

=  , [1, 17], the approximate values for critical crack length,

and by introducing the values of conventional yield stress, R p0,2

a c , can be calculated.

Testing temperature.  C

Specimen mark PM-1-1n PM-1-2n PM-1-3n PM-2-1n PM-2-2n PM-2-3n Specimen mark PM-1-1e PM-1-2e PM-1-3e PM-2-1e PM-2-2e PM-2-3e

Critical J-integral. J Ic, kJ/m 2

Critical stress intensity factor, K Ic, MPa m 1/2

Critical crack length, a c , mm

60.1 63.9 58.6 43.2 44.7 45.3

117.8 121.4 116.3

38.5 40.8 37.5 40.0 41.4 41.9

20

87.2 88.7 89.2

540

Table 8: Values of K Ic

notched specimens in new PM.

Testing temperature,  C

Critical J-integral, J Ic , kJ/m 2

Critical stress intensity factor, K Ic , MPa m 1/2

Critical crack length, a c , mm

47.8 42.1 40.7 24.5 22.7 21.8

105.0

41.7 36.8 35.6 30.8 28.6 27.4

20

98.6 96.9 65.6 63.2 61.9

540

Table 9 : Values of K Ic

notched specimens in exploited PM.

The characteristic diagrams F-  , and J-  a for specimen taken out from the sample of new PM are given in Fig. 6 (left) for specimen marked as PM-1-1n tested at room temperature, and in Fig. 7 for specimen marked as PM-2-1n tested at the temperature of 540  C, [1].

16

250

PM-1-1n 20 o C

PM-1-1n 20 o C J Ic = 60,1 kJ/m 2

200

12

150

8

100 J, kJ/m 2

F, kN

J

4

Ic

50

0

0

0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

 , mm  a, mm Figure 6 : F- δ (left) and J- Δ a (right) diagrams of specimen PM-1-1n.

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