Abstract
Organic inhibitors have been considered as an effective way to control the corrosion of carbon steel weldment in an acidic environment. This work proposes a new green organic inhibitor made of extract of rambutan fruit (Nephelium lappaceum) peel and aims at analyzing its corrosion inhibitor properties and protection mechanism. Specimens of carbon steel weldment were tested for their corrosion by using electrochemical and immersion methods in 1 M HCl solution containing 0 to 6 g/L of Nephelium peel (NP) extract. Results showed that, in the same solution, the corrosion rate was measured to be higher on the weld metal zone than that of base metal zone, which could be related to the coarser grain of the weld metal zone and the stability of the formed oxide layer. The addition of NP extract was found to increase the stability of the oxide layer, thus increasing the corrosion resistance of the specimens. The maximum inhibition efficiency of the NP extract was reached at 97% for weld metal with 5 g/L of extract, at 80% for the heat affected zone with 5 g/L, and at 70% for base metal with 4 g/L. This work reveals the particularity of different weldment zones to the different needs of inhibitor concentration for obtaining the optimum corrosion protection.
Highlights
In a chloride-containing acidic environment, corrosion becomes the principal cause of many failures in steel structures [1,2]
This work reveals a change in the corrosion behavior of steel weldment after being inhibited by rambutan fruit (Nephelium lappaceum, Nephelium peel (NP)) extract
The NP extract acts as a mixed-type inhibitor that contributes to the increase of oxide layer stability, increasing the corrosion resistance of the weldment
Summary
In a chloride-containing acidic environment, corrosion becomes the principal cause of many failures in steel structures [1,2]. Compositional segregation, residual stress, and microstructural variation in the welding zone lower the corrosion resistance of the weldment [3]. Microstructural variation, such as grain size and shape, influences the active passive response of the corroded surface of a weldment, where a finer grain may lead to a lower rate of localized corrosion but a higher rate of uniform corrosion [4]. Weldment corrosion in a chloride-containing acidic environment can be controlled by employing inhibitors This inhibitor should be able to reduce the susceptibility of hydrogen uptake that is released during the cathodic reaction, reducing the risk of hydrogen-induced cracking in the weldment [5]
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