Possibility of Corrosion Monitoring Resistance of Austenitic Steel for Ship Construction

Abstract

The article presents the investigation results on possibility of electrochemical corrosion monitoring of the 1.3964 steel used for ship construction according of the patent Pl 216723. The patent's assumption describes the method of on-line registration of electrochemical potential specifying the protective effectiveness of a thin oxide layer formed spontaneously on the steel surface. Essentials drop of the potential's value with respect to the stationary one indicates layer cracking and initiation of pitting corrosion. Such a corrosion can be initiated by salinity and temperature of seawater and/or by a mechanical factor (strain). The carried out measurements of the potential and mechanicalelectrochemical teats made it possible to determine the stress level causing the crack of oxide layer and initiation of corrosion processes in the steel. Thereby, the mechanical properties (Rm and A5) thin passive oxide layers investigated steel. Application of Electrochemical Impedance Spectroscopy (EIS) in the laboratory allows monitoring of weakness (stratification) of the film as a stage preceding to fracture [1, 2]. Stress cracking of the protective oxide layer on the 1.3964 steel takes place beyond the exploitation zone (above the tensile strength) and there is no indication to monitor the corrosion resistance on ship construction made of this stainless steel. However, in specific cases when temperature of the steel exceeds 40 o C, application of the monitoring may be justified.