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Electrochemical noise characterisation of base metal and weld metal of an ASTM 516 steel in H 2 S containing environment
Author(s) -
Pinto J. E. R.,
Ponciano J. A. C.
Publication year - 2001
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/1521-4176(200103)52:3<201::aid-maco201>3.0.co;2-v
Subject(s) - welding , metallurgy , electrochemistry , metal , materials science , electrochemical noise , chemistry , composite material , electrode
The inspection of steel structures exposed to sour environments has revealed a higher incidence of cracks at welded joints. This tendency is associated to several factors, including residual stresses, different microstructures and dissimilar electrochemical behaviour between base metal and weld metal. The crack incidence in general is attributed to hydrogen absorption due to the cathodic reduction of this species. In this work, the electrochemical noise behaviour of weld and base metals of an ASTM 516, C‐Mn steel exposed to a H 2 S containing environment is studied. Current and voltage fluctuations are measured and the spectral noise impedance (R sn ) is determined. The current fluctuations are measured by means of a Zero Resistance Ammeter and voltage fluctuations with respect to a calomel reference electrode. In this case, residual stresses and microstructures of both materials can be assumed as secondary factors to hydrogen cracking. However, electrochemical noise measurements indicated the existence of different electrochemical processes for base metal and weld metal in the environment considered.