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Fatigue crack propagation in API 5L X‐70 pipeline steel longitudinal welded joints under constant and variable amplitudes
Author(s) -
BELTRÃO M. A. NEVES,
CASTRODEZA E. M.,
BASTIAN F. L.
Publication year - 2011
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.2010.01521.x
Subject(s) - amplitude , base metal , welding , materials science , constant (computer programming) , paris' law , ultimate tensile strength , structural engineering , composite material , fracture mechanics , metallurgy , crack closure , physics , engineering , optics , computer science , programming language
Fatigue crack propagation (FCP) under constant and variable amplitude loading in base metal (BM), weld metal (WM) and heat affected zone (HAZ) of longitudinal welded joints of an API X‐70 pipeline steel was investigated. Constant amplitude loading tests were performed at R = 0.1 and 0.5, whereas for variable amplitude testing single peak tensile overloads (OLs) alternating between 75 and 100% of maximum load were applied at 2.5 mm intervals in crack growth. Results of SE(B) specimens tested under constant and variable amplitude loading revealed that BM, WM and HAZ regions subjected to R = 0.5 and low Δ K ‐values presented the highest crack growth rates. At higher Δ K values FCP rates in all the studied regions were similar and the R effect on FCP rate was no more observed. Crack growth retardation due to OLs was observed at the three studied regions, showing a decrease on the FCP delay with a decreasing on Δ K .