Study On Corrosion Behavior Of13Cr In Acid

Autoclave tests and SEM, EDS, XPS and laser scanning confocal microscope technologieswere used to study the corrosion behavior of13Cr martensitic stainless steel in differenttemperature fresh acid environment, and the corrosion behavior in different temperature, residualacid flowback time and the pH value spent acid environment. Through studing the corrosionbehavior of13Cr martensitic stainless steel in different temperature hydrochloric acid byelectrochemical test, as well as corrosion inhibitor and13Cr martensitic stainless steel in freshacid environment matching.The results showed that：in the simulates fresh acid environment, with the temperatureincreased, uniform and localized corrosion rates of13Cr martensitic stainless steel wereincreased.In the range of60℃~140℃, uniform corrosion rate of13Cr martensitic stainless steelwere lower than the level range of SY/T5405-1996"Acidified with corrosion test methods andperformance evaluation" standard. When the temperature increased to160℃, uniform corrosionrate increased rapidly In the range of60℃~120℃, there were no obvious localized corrosion onthe surface of13Cr martensitic stainless steel. In the range of120℃~180℃,the surface of thespecimen were appeared different degree of pitting corrosion, with the temperature increased, thepit depth and density increased.In the simulates spent acid environment, In the range of60℃~160℃, uniform corrosionrate of13Cr martensitic stainless steel were lower than the level range of SY/T5405-1996"Acidified with corrosion test methods and performance evaluation" standard. Whenthe temperature at60℃to140℃,corrosion rate increased smaller with the temperature increased. When the temperature reached160℃, the uniform corrosion rate increased significantly.Compared with the fresh acid corrosion, low temperature (lower than120℃) spent acidcorrosion test, the maximum pitting depth were increased. After the high temperature spent acidtest, the maximum pitting depth increasing trend was not obvious.With the temperature rises, theincreasing tendency of the maximum pitting depth is not obvious. With residual acid flowbackprolonged, uniform corrosion rate were lower than the standard level, the increasing tendency ofthe maximum pitting depth is not obvious. With pH values of the spent acid increased, uniformcorrosion rate and the maximum pitting depth of13Cr martensitic stainless steel were decreased.13Cr martensitic stainless steel at120℃, the product film after test exists obvious stratification, the outer layer was mainly composed of Cr(OH)3, FeOOH and Cu element, the inner layer16.8nm deep was mainly composed of Cr2O3, FeCl2and elemental Cu and a small amount ofCuO.Polarization curves in15%hydrochloric acid solution showed that: with the temperatureincreased, corrosion potential of13Cr martensitic stainless steel decreased and corrosion currentdensity increased, so corrosion rate increased, corrosion performance degradation; the EISshowed that the two time constants appeared on the impedance spectra, namely high frequencycapacitive arcs and low frequency inductive arc. With temperature increased, the polarizationresistance were reduced, the corrosion rate increased. Corrosion inhibitor significantly reducedthe corrosion current density and the corrosion rate of13Cr martensitic stainless steel.