Electrochemical polarization and stress corrosion cracking behaviors of a pipeline steel in dilute bicarbonate solution with chloride ion

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00112-9· OSTI ID:99242

Liu, X; Mao, X ^[1]

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1. Univ. of Calgary, Alberta (Canada). Dept. of Mechanical Engineering

The electrochemical and stress corrosion cracking behavior of Grade 550 (X-80) pipeline steel with coating disbandments was studied in a range of bicarbonate solutions using a potentiodynamic polarization technique and slow strain rate test. The shape of the polarization curves were found to vary with bicarbonate concentration. Increase in bicarbonate concentration results in a wider passive region and a more noble breakdown potential. Low concentrations of chloride ion in bicarbonate greatly affect the polarization characteristics and can cause the elimination of passivity in specific solutions. Tensile specimens were pulled at constant strain rate {dot {epsilon}} = 10{sup {minus}6}/sec. under potential control ranging from {minus}350 mV to {minus}900 mV (SCE) in NS-4 solution (dilute bicarbonate solution with chloride ion). Fracture surface of the specimens were examined under scanning electron microscopy. Overall fracture is ductile dimple, however, transgranular stress corrosion cracking has been found in the edge of specimen for the sample with potential controlled at {minus}800 mV, {minus}750 mV and {minus}650 mV (SCE).

• OSTI ID: 99242
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 1 Vol. 33; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACID CARBONATES
CARBON STEELS
CARBONATES
CHLORIDES
ELECTROCHEMISTRY
FRACTURE PROPERTIES
PASSIVITY
PIPELINES
SCANNING ELECTRON MICROSCOPY
STRESS CORROSION