| Corrosion is easy to take place during the working process of the castedZG0Cr18Ni9Ti suspension bracket. Using optical microscope and scanningelectron microscopy (SEM), the corrosion mechanism of ZG0Cr18Ni9Ti wereobtained. In order to increase the corrosion resistence of this component, thedacromet treatment was employed in this study. In addition, the corrosiveproperties of the samples treated by dacromet treatment were studied by neutralsalt spray test and polarization curve test.The experimental results showed that the corrosion specie of ZG0Cr18Ni9Tisubway suspension brackets in the process of using was pitting corrosion, becausethere were chloride ions in the coastal air. By the casting surface compositionanalysis, microstructure investigation, the surface structure observation showedthat the passivation film on the surface was incomplete and discontinuous becauseof the microporous on the surface of the casting.The NSS test results showed that specimens of ZG0Cr18Ni9Titreated bydacro surface can experience144h without rust in neutral salt spray test. Thedacromet coating was consisted of multilayer flaky zinc, and aluminium, whichcontroled the moisture and oxygen infiltration rate on the surface of the substrate,and provided a good protection to the steel substrate.Polarization curve test can demonstrate the corrosion speed of the casting.The polarization curve result showed that the corrosion speed of the dacromettreated casting alloy was slower than the acid dipping and passivating treatedcasting.The results showed that the dacromet process can protect the ZG0Cr18Ni9Ticasting alloy from being cored in use. The dacromet process was proposed toapplication on the ZG0Cr18Ni9Ti casting alloy and a dacromet production linewas established．... |
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