Influence of local brittle zone size on the heat affected zone toughness of structural steel for offshore applications
- CEFET/CSF-RJ, Rio de Janeiro (Brazil)
- DCMM/PUC-Rio, Rio de Janeiro (Brazil)
- PEMM-COPPE/UFRJ, Rio de Janeiro (Brazil)
The use of microalloyed steels in offshore structures has emphasized the necessity for a thorough understanding of the problems associated with heat affected zone (HAZ) brittle fracture susceptibility in these alloys. The study of this zone is of interest because of the tendency to form local brittle zones (LBZ) associated with the coarse grain region adjacent to the fusion line. A difficulty in analyzing HAZ fracture toughness results obtained for specimens of multipass weld runs results from complex crack propagation path which typically passes through various microstructural regions during the test, leading to extensive scatter in the resulting data. The fatigue crack propagation front is analyzed within the LBZ for BS4360 G50 structural steel obtained using a variable angle bead in groove technique to minimize the scatter in the crack opening displacement (CTOD) values from tests at {minus}20 C. A toughness decrease was correlated with increasing proportions of crack propagation within the LBZ, which was, in turn, correlated to the amount of coarse grained region sampled by the fatigue pre-crack tip, exhibiting a constant minimum value exceeding a determined length. The simulation technique minimized scatter in CTOD data, allowing an analysis of total LBZ crack path length on HAZ toughness.
- OSTI ID:
- 442979
- Report Number(s):
- CONF-950682--; ISBN 0-87170-567-2
- Country of Publication:
- United States
- Language:
- English
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