The inhibiting effect of some organic compounds at 0.1 mM concentration on the stress corrosion cracking (SCC) of a C steel in 5% NaCl + 0.5% acetic acid in the presence of 1 mM thiosulphate at 25°C was studied. The inhibition of these compounds on the uniform corrosion was evaluated by recording anodic and cathodic polarisation curves after 1 and 24 hour immersion of the electrode in the aggressive solutions. Slow strain rate tests were performed at a strain rate of 1 x 10-6s-1. The hydrogen permeation currents after 24 hour of immersion of steel were determined. The examined compounds exerted an inhibiting action towards the general corrosion, ranging between 74 and 96%. The % inhibiting efficiencies (IE), calculated from the permeation current values of DDQB, DDPC and IMI, were almost the same as the %IE towards the general corrosion. In the presence of the other compounds %IE on the hydrogen permeation was lower than that towards the general corrosion. DDQB, DDPC and IMI were able to reduce the stimulating action of thiosulphate completely. The other compounds increased alpha values, but they were unable to inhibit SCC completely. The inverse linear relationship between alpha and hydrogen permeation current values evidenced a strict correlation between hydrogen permeation and SCC susceptibility in these solutions.

SCC inhibition of a C steel in acidic 5% NaCl in the presence of thiosulphate.

ZUCCHI, Fabrizio;TRABANELLI, Giordano;MONTICELLI, Cecilia;GRASSI, Vincenzo
1999

Abstract

The inhibiting effect of some organic compounds at 0.1 mM concentration on the stress corrosion cracking (SCC) of a C steel in 5% NaCl + 0.5% acetic acid in the presence of 1 mM thiosulphate at 25°C was studied. The inhibition of these compounds on the uniform corrosion was evaluated by recording anodic and cathodic polarisation curves after 1 and 24 hour immersion of the electrode in the aggressive solutions. Slow strain rate tests were performed at a strain rate of 1 x 10-6s-1. The hydrogen permeation currents after 24 hour of immersion of steel were determined. The examined compounds exerted an inhibiting action towards the general corrosion, ranging between 74 and 96%. The % inhibiting efficiencies (IE), calculated from the permeation current values of DDQB, DDPC and IMI, were almost the same as the %IE towards the general corrosion. In the presence of the other compounds %IE on the hydrogen permeation was lower than that towards the general corrosion. DDQB, DDPC and IMI were able to reduce the stimulating action of thiosulphate completely. The other compounds increased alpha values, but they were unable to inhibit SCC completely. The inverse linear relationship between alpha and hydrogen permeation current values evidenced a strict correlation between hydrogen permeation and SCC susceptibility in these solutions.
inhibition; stress corrosion cracking; carbon steel; acidic NaCl solution; thiosulphate
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/1196541
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