Electrochemical Potentiodynamic Reactivation: Development and Applications of the EPR Test

Abstract

The EPR test, designed to examine of the susceptibility to nonuniform, primarily intergranular corrosion, ranks among the more successful testing technique developments relating to stainless steels and alloys. One of its numerous advantages is that it lends itself to non-destructive, on-site examination. EPR enjoyed wide expansion over the years since first conceived by Čihal in 1969. Recent EPR measurements tend to focus on (1) double and/or single loop EPR as a modern technique used to establish the resistance of stainless steels and alloys to intergranular corrosion; (2) detecting integranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) susceptibility in alloy steels and nickel alloys for nuclear engineering applications; and (3) studies of grain boundary precipitation and other minute local changes to alloy composition and structure.

Influence of microstructure and surface treatment on the corrosion resistance of martensitic stainless steels 1.4116, 1.4034, and 1.4021

“…It was shown that the EPR test promises good detection of chromium depleted zones for different states of low carbon stainless steels with up to 16% chromium . Grain boundary precipitation and other minute local changes to alloy composition and structure influence the electrochemical characteristics of the EPR test and can also provide important information on secondary phases and their distribution . The differences in the chemical composition of the alloys used in this study suggested that the EPR test would be a usable method for comparison of the impact of microstructural differences on the corrosion resistance.…”

Enhancement of intergranular corrosion resistance of type 304 stainless steel through laser shock peening

“…Hence, the charge passed during reactivation cycle is considered as an index of chromium depletion. Degree of sensitisation (DOS), as determined from DL-EPR test, is expressed as %DOS = ( I r / I a ) × 100, where I a = maximum activation current in the forward scan and I r = maximum reactivation current in the reverse scan [12].…”

Quantitative analysis of susceptibility to intergranular corrosion in alloy 625 joined by friction stir welding

“…To evaluate in a quantitative manner the sensitivity to intergranular corrosion, the conventional immersion method and electrochemical technique DL-EPR were used. The latter was developed by Cihal [12][13][14] to characterise the material sensitisation.…”