Research On Resistance Of B450nbre Steel To Atmospheric Corrosion

B450NbRE steel is of rare earth weathering steel for Chinese character. The steel contain so many kind of alloy elements, which is the component character of the steel. In order to improve the resistence of B450NbRE steel to atmosphere corrosion, mechanism of action to the property for every element should be researched completely. By lab accelerated corrosion experiment, electro-chemical analysis and X-ray diffraction analysis, effect to corrosion rate, polarization curve and AC impedance of B450NbRE steel for every of all the elements RE, Nb, Ni, V, Mn, Cu, Cr was researched completely, under the condition of this experiment, main conclusions were given as following:(1) Microcontent of RE can reduce annual corrosion rate of B450NbRE steel, improve the resistence of B450NbRE steel to atmosphere corrosion. natural corrosion current density of B450NbRE steel is lower, natural corrosion potential is higher, charge transfer resistence in high frequency is larger, and the resistence to atmosphere corrosion is better, when RE content changed from 0.0048% to 0.0075%.(2) All of the elements of Nb, Ni, V, Cu can reduce annual corrosion rate of B450NbRE steel, improve the resistence of B450NbRE steel to atmosphere corrosion. The effectiveness is obvious for Ni and Cu. With increase of Ni, V, Cu in the steel, natural corrosion current density of B450NbRE steel become lower, natural corrosion potential become higher, charge transfer resistence in high frequency become larger, With increase of Nb in the steel, little changeof Polarization curve can be found, but charge transfer resistence in high frequency become larger.(3) Cr or Mn can increase annual corrosion rate of B450NbRE steel at a certern extent, they are bad for improving the resistence of B450NbRE steel to atmosphere corrosion. With increase of Cr or Mn, charge transfer resistence in high frequency of steel become lower, in addition, natural corrosion current density become larger and natural corrosion potential become lower because of the existence of Mn. With increase of Cr in the steel, little changeof Polarization curve can be found.(4) RE can makeδ-FeOOH and Fe;O4 changed intoγ-FeOOH in rusty scale, and improve the resistence of B450NbRE steel to atmosphere corrosion.(5) Nb. Ni and Cu can makeδ-FeOOH and Fe3O4 changed intoγ-FeOOH andα-FeOOH in rusty scale, and improve the resistence of B450NbRE steel to atmosphere corrosion.Little effective to phase composition of rusty scale can be found because of the existence of Cr. Cr can not makeδ-FeOOH and Fe3O4 changed intoγ-FeOOH orα-FeOOH.