Effect of Cu Content on Corrosion Behavior of Q420 Steel in an Artificial Solution of Bottom Plate Environment of Cargo Oil Tanks
Trial low alloy steels based on Q420 steel were prepared by alloying with a little amount of Cu 0.5％,1.0％,1.5％and 2.0％,mass fraction.Then their corrosion behavior was assessed in an artifi-cial solution(i.e.10％NaCl(mass fraction)solution with pH 0.85)as a simulation of the corrosive environ-ment of the bottom plate of cargo oil tanks were studied by means of immersion tests,SEM,XRD,TEM,and other methods.The results indicate that the low alloy steel with 1.0％Cu of a microstructure of ferrite and pearlite can ensure excellent corrosion resistance at the strength level of Q420 steel.The addition of Cu plays a crucial role in the corrosion resistance of the low alloy steel.As the soaking time prolongs,the corrosion rate of the trial steels with 5 different Cu-content shows an overall downward trend.The trial low alloy steel with 1％Cu presents a corrosion rate of 0.29 mm/a,which is 43％lower than the Q420 benchmark steel.The study proves that the addition of Cu has a positive effect on the uniform corrosion of Q420 in the simulated bottom plate environment of cargo oil tanks.
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