Hydrogen-Induced Cracking Caused by Galvanic Corrosion of Steel Weld in a Sour Environment.

Jin Sung Park,Sung Jin Kim,Jin Woo Lee

doi:10.3390/ma14185282

Jin Sung Park, Sung Jin Kim + Show 1 more

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https://doi.org/10.3390/ma14185282

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Abstract

This study examined the hydrogen-induced cracking (HIC) caused by galvanic corrosion of an ASTM A516-65 steel weld in a wet sour environment using a combination of standard immersion corrosion test, electrochemical analyses, and morphological observation of corrosion damage. This study showed that the weld metal has lower open circuit potential, and higher anodic and cathodic reaction rates than the base metal. The preferential dissolution and much higher density of localized corrosion damage were observed in the weld metal of the welded steel. On the other hand, the presence of weldment can make steel more susceptible to HIC, specifically, in areas of the base metal but not in the weld metal or heat affected zone, which is in contrast to typical expectations based on metallurgical knowledge. This can be explained by galvanic corrosion interactions between the weldment and the base metal, acting as a small anode and a large cathode, respectively. This type of galvanic couple can provide large surface areas for infusing cathodically-reduced hydrogen on the base metal in wet sour environments, increasing the susceptibility of welded steel to HIC.

Highlights

Materials 2021, 14, 5282. https://Hydrogen degradation of ferrous alloys has attracted considerable attention in the scientific and engineering community for more than 100 years [1,2,3]
This work elucidates the preferential occurrence of hydrogen-induced cracking (HIC) in the base metal (BM) in the welded steel under wet sour corrosion with a series of experimental results
The preferential occurrence of HIC in the BM is caused primarily by the fact that the chemical composition of weld metal (WM), which was optimized for mechanical properties, is slightly anodic to the BM

Summary

Introduction

Hydrogen degradation of ferrous alloys has attracted considerable attention in the scientific and engineering community for more than 100 years [1,2,3]. On the other hand the welding consumable is adopted considering mostly the mechanical properties of the base metal (BM) This welding consumable does not guarantee the WM will have high resistance to corrosion or corrosion-induced HAC. In this regard, Pagotto et al [17] reported a much higher anodic dissolution current at welds relative to the BM of carbon steel in a neutral aqueous environment, employing a scanning vibrating electrode technique (SVET). The cracking problem of the BM became worse in the presence of the WM compared to the unwelded steel sample This is closely associated with the formation of a galvanic couple with the WM and BM in an acidic aqueous environment. The National Association of Corrosion Engineers (NACE) standard HIC test, diffusible hydrogen measurement, and several electrochemical evaluations were conducted to clarify the mechanistic reason for the more serious damage by HIC in the BM, which can be protected galvanically

Experimental Procedure

Results and Discussion

Summary