Electrochemical Corrosion Behavior of AISI 409L Stainless Steel Aluminized by Hot-Dip Coating Method in Automotive Exhaust Gas Solution

摘要

This paper focuses on the pitting resistance of hot-dip aluminized (HDA) stainless steel after the depletion of the coating layer formed in the exhaust condensed solution. HDA stainless steel is composed of a coating layer, an interdiffusion layer, and a substrate. In the interdiffusion layer which is mainly composed of Al-7(Fe,Cr)(2)Si and (Fe,Cr)(Al,Si)(3), microcracks were observed in the (Fe,Cr)(Al,Si)(3) layer. From electrochemical tests, the corrosion potential of the Al-10Si coating-removed 409L is higher than that of the interdiffusion layer-removed 409L. The pit depth of the substrate (anode) exposed by microcracks of the interdiffusion layer (cathode) is drastically increased when the coating layer is extinct.