Field applicable methods for intergranular corrosion testing of stainless steels structures

Abstract

Determination of the susceptibility of austenitic stainless steel X5CrNi18-10 to intergranular corrosion (IGC) is performed by measuring the corrosion potential Ecorr in a drop of a test solution with specific chemical composition. It has been shown that a good correlation exists between the results obtained by Ecorr measurements in a drop of the test solution and the results obtained by the double loop electrochemical potentiokinetic reactivation method (DL EPR). The results are confirmed by SEM analysis of the stainless steel surface after the IGC test. The method of Ecorr measurements is a simple non-destructive method that provides qualitative information on the susceptibility of the stainless steel to IGC. The DL EPR method is a quantitative method that can determine small differences in the susceptibility of stainless steel to IGC. Simple and cheap equipment is required to perform Ecorr measurements. The method is easy to perform on stainless steel structures in the field.

Određivanje sklonosti austenitnog nerđajućeg čelika X5CrNi18-10 prema interkristalnoj koroziji izvršeno je na osnovu merenja korozionog potencijala Ekor u kapi rastvora definisanog sastava. Pokazano je da postoji dobra saglasnost dobijenih rezultata sa rezultatima ispitivanja interkristalne korozije primenom metode elektrohemijske potenciokinetičke reaktivacije sa povratnom petljom (DL EPR). Dobijeni rezultati su potvrđeni SEM analizom površine čelika posle ispitivanja interkristalne korozije navedenim metodama. Metoda merenja Ekor u kapi rastvora je jednostavna, nerazarajuća metoda koja daje kvalitativne podatke o sklonosti čelika prema interkristalnoj koroziji, dok je DL EPR metoda kvantitativna, kojom se mogu odrediti male razlike u sklonosti nerđajućih čelika prema interkristalnoj koroziji. Za izvođenje ispitivanja metodom merenja Ekor u kapi rastvora potrebna je znatno jeftinija i jednostavnija oprema. Ova metoda se lako izvodi na gotovim konstrukcijama, na terenu.