The effects of crystallographic texture and hydrogen on sulfide stress corrosion cracking behavior of a steel using slow strain rate test method

Abstract

The effects of pre-charged hydrogen inside steel and the hydrogen ions on its surface on the sulfide stress corrosion cracking (SSCC) behavior was studied by slow strain rate tests. The specimen had an ASTM grain size number of about 11. Most of precipitates were 30–50 nm in size, and their distribution density was about 106 mm−2. The crystallographic texture consisted of major α-fiber (〈110〉//RD) components with a maximum peak at {115}〈110〉 relatively close to {001}〈110〉, and minor γ-fiber (〈111〉//ND) components with a peak slightly shifted from {111}〈112〉 to {332}〈113〉. Hydrogen was pre-charged inside the steel by a high-temperature cathodic hydrogen charging (HTCHC) method. SSCC and corrosion tests were carried out in an electrolytic solution (NaCl: CH3COOH: H2O: FeCl2 = 50: 5: 944: 1, pH = 2.7). The corrosion potentials and the corrosion rates of the specimen without hydrogen charging for 24 hours were −490 mVSHE and 1.2 × 10−4 A cm−2, and those with charging were −520 mVSHE and 2.8 × 10−4 A cm−2, respectively. The corrosion resistance in the solution with 1000 ppm iron chloride added was decreased significantly, such that the corrosion potential and corrosion rate were −575 mVSHE and 3.5 × 10−4 A cm−2, respectively. Lower SSCC resistance of the pin-hole pre-notched specimen was observed at the open circuit potential than at the 100 mV cathodically polarized condition. Pre-charged hydrogen inside of the specimen had a greater influence on the SSCC behavior than hydrogen ions on the surface of the specimen during the slow strain rate test.