Transformation between localized and general corrosion behavior of die‐cast AZ91D magnesium alloy in 3.5 wt% NaCl aqueous solutions

Abstract

Transformation behavior between localized and general corrosion of die-cast AZ91D magnesium alloy in anodizing processes was investigated by galvanostatic polarization. The results revealed that, at electric current density 5, 10, and 20 mA/cm 2 , a localized corrosion state appears on the specimen surface in the initial stage (10 min), and is changed into general corrosion with the galvanostatic measurement time. On the other hand, the increase in electric current density has caused the increase of the corroded area on the specimen surfaces at the same galvanostatic measurement time. In comparison, the appearance of localized corrosion based on general corrosion can be attributed to the localized absorption along with enhanced activity and reactivity of Cl − at the higher electric current density (10 and 20 mA/cm 2 ). Meanwhile, the penetration of Cl − throughout the corrosion products has caused the destruction of the integrity of these corrosion products, which promotes the continuous growth of the localized corrosion pits under the galvanic effect. K E Y W O R D S

Model identification of durability degradation process of concrete material and structure based on Wiener process

“…Many experiments and theoretical analyses have proved that the degradation process of concrete structure performance is a process superimposed by many random and small losses, and it will eventually exceed the failure threshold to the failure, so the degradation process of structure performance can be regarded as a stochastic process with uncertainty. Meanwhile, the stochastic law is important supplement to the deterministic degradation mechanism (Xiao et al., 2020; Yang et al., 2019; Zhang et al., 2019). Therefore, using a stochastic process to describe the degradation process of a structure is necessary which can really reflect better the actual situation of the structure.…”

“…Wiener process can describe the nonmonotonic degradation process of a structural system and has excellentcomputational analysis characteristics. Therefore, Wiener process model is one of the most widely used models in structural reliability modeling and analysis based on performance degradation (Zhang et al., 2019, 2020). Doksum et al., 1992 introduced Wiener process into engineering field for the first time, and studied the problem of accelerated degradation life test model of Wiener process with variable pressure.…”