Corrosion fatigue

Engineering

Wear resistance

Metallurgy

Materials science

Galvanic cell

Ferrite (magnet)

Pearlite

Physical chemistry

Cathodic protection

Mechanical engineering

Microstructure

Austenite

Composite material

Corrosion

Chemistry

Electrode

Anode

Cementite

Oil tank

Materialia

The influence of cementite spheroidization on the corrosion resistance of a pearlitic steel used as cargo oil tank under the simulated bottom plate environment was investigated by employing microstructural characterizations, electrochemical measurements and gravimetric tests. The results indicate that for the as-forged pearlitic steel with the gradual accumulation of lamellar cementite on the surfaces, the galvanic effect between the anodic ferrite and the cathodic cementite is enhanced during corrosion evolution. This leads to intense corrosion acceleration. However, after cementite spheroidization, the discrete spherical cementite is easy to separate from the matrix when the surrounding ferrite matrix is dissolved. The area ratio of cathodic to anodic keeps at a stable value, and both the anodic dissolution of iron and cathodic HER are retarded by cementite spheroidization. As a result, the galvanic acceleration effect is restrained and the corrosion resistance of the pearlitic steel is improved significantly.

Effect of cementite spheroidization on improving corrosion resistance of pearlitic steel under simulated bottom plate environment of cargo oil tank