PSI - Issue 43

Marie Ohanková et al. / Procedia Structural Integrity 43 (2023) 300–305 Author name / StructuralIntegrity Procedia 00 (2022) 000 – 000

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(base on correlation data analysis from Czech material standard for steel 15 128). However, the non-exposed sample (NE) segment reaches the -20 % tolerance band below the applied stress of 250 MPa and exposed sample (BM1, BM2) is probably added to it, but only at a applied stress below 150 MPa.

300

500

250

400

50 Notch toughness, KCV (Jcm -2 ) 100 150 200

BM1 transverse BM1 longitudinal WM longitudinal BM2 transverse NE transverse

300

Stress,  (MPa)

BM1 transverse BM1 transverse 528 °C WM longitudinal BM2 transverse NE transverse NE transverse 528 °C

200

middle

100

outer middle inner

0

0

0 5 10 15 20 25 30 35

-50

0

50 100 150 200

Strain,  (%)

Temperature, T (°C)

b

a

400

P1 = 21896 ± 797 P2 = -106 ± 593 P3 = -948 ± 147 LMP = P1 + P2 log(  ) + P3 log 2 (  )

350

300

250

200

Stress,  (MPa)

150

NE (528 °C) BM1 (528 °C) BM2 (528 °C) Fürbacher (2006-) Cr-Mo-V steel 15128

100

- 20 %

50

0

12000 14000 16000 18000 20000 22000 Larson-Miller Parameter (C = 16.9 ± 0.5)

c

d

Fig. 1. Result of (a) tensile tests; (b) Charpy tests; (c) creep tests; (d) hardness measurement.

However, considering that the values of creep behavior of Cr-Mo-V steel 15 128, presented in Czech material standard and by F ür bacher (2006-) are obtained on cylindrical bodies, while the creep tests of pipeline samples plotted in Fig. 1c were performed almost on flat bars with diameters 5 x 3 x 55 mm, the difference between the normalized master curve and the analyzed samples can be even at high stress realistically smaller. The hardness measurement revealed that the hardness of the outer surface practically corresponds to the hardness of the center of the wall thickness of both exposed and non-exposed samples (about 150 HV10). Only at the inner surface it decreases by about 10 HV10 units. The profile of hardness through the welded joint, see Fig. 1d, resulted