Transgranular stress corrosion cracking of X-60 pipeline steel in simulated ground water

Journal Article · Mon Mar 01 04:00:00 EST 1999 · Corrosion

DOI:https://doi.org/10.5006/1.3283991· OSTI ID:349904

Zhang, X Y ^[1]; Lambert, S B; Plumtree, A ^[2]; Sutherby, R ^[3]

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1. Menesco Aero Space, Mississauga, Ontario (Canada)
2. Univ. of Waterloo, Ontario (Canada). Dept. of Mechanical Engineering
3. Nova Gas Transmission, Ltd., Calgary, Alberta (Canada)

An investigation was carried out on API X-60 steel specimens with multiple edge cracks to determine transgranular stress corrosion crack (TGSCC) growth rates in simulated ground water (NS-4 solution). Loading and environmental conditions were similar to those for buried natural gas pipelines in service. Specimens were loaded statistically or cyclically in cantilever bending with the maximum crack tip stress intensity factor (K{sub max}) varying from 34 MPa{radical}m to 38 MPa{radical}m. Static tests were carried out for periods extending to 111 days. For the cyclic tests, which lasted up to 378 days, the stress ratio (R = minimum/maximum load) was controlled between 0.5 to 0.9, with frequencies ranging from 40 cycles/day to 5,000 cycles/day. TGSCC with crack features similar to those found in the field was produced successfully in the laboratory. Depending upon the loading conditions and test period, the crack growth varied from {approximately}10 {micro}m to 1,800 {micro}m, corresponding to maximum average crack growth rates from 6.1 {times} 10{sup {minus}10} mm/s to 2.6 {times} 10{sup {minus}7} mm/s. For a low R ratio and high frequency, the observed growth was the result of corrosion fatigue. Under the conditions of a static load or high R ratio and low frequency, growth was caused by TGSCC. A superposition model for crack growth was proposed and applied to the experimental data, giving good agreement between the predicted and observed crack growth rates.

• OSTI ID: 349904
• Journal Information: Corrosion, Journal Name: Corrosion Journal Issue: 3 Vol. 55; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
36 MATERIALS SCIENCE
CRACK PROPAGATION
FRACTURE MECHANICS
FRACTURE PROPERTIES
GROUND WATER
MATHEMATICAL MODELS
PIPELINES
STEELS
STRESS CORROSION
STRESS INTENSITY FACTORS