Effects of AC Interference on Passive Metals Corrosion

EFFECTS OF AC-INTERFERENCE ON PASSIVE METALS CORROSION

 Abstract:

AC-induced corrosion continues to be a controversial subject and a full

agreement on influencing parameters and mechanism has not yet been achieved.

The influence of AC-induced interference on the localised corrosion

resistance of passive metals is discussed on the basis of laboratory test

results. Tests were performed on stainless steel with different chemical

composition (PREN from 18 to 47) in soil-simulating solution and on carbon

steel in alkaline solution (under cathodic protection of carbon steel, the

local pH at the interface soil-steel is higher than 10, so carbon steel is

in passive condition). Potentiodynamic tests were also carried out to

analyse the effects of AC stationary interference on passivity current

density. Applied AC was in the range of 10 A/m2 to 500 A/m2. Results allow

to evaluate the effect of AC on: time-to-corrosion, AC critical current

density and corrosion morphology.