Corrosion Coupon Strength Effects on Corrosion Susceptibility in Different Environments (C2026-00398)

Joshua Jackson, Alexandra Carreno, Ali Koochekzadeh, Will Ritter

Corrosion coupons provide a convenient, cost-effective way to monitor the long-term corrosivity of pipelines, wells, tanks, and other industrial applications. Generally speaking, the coupons are fabricated in the annealed or low-strength state unles otherwise specified by the customer. For steels and main other alloys, this puts them in a condition where they are not susceptible to environmentally assisted cracking (EAC) modes such as stress corrosion, hydrogen embrittlement, or corrosion fatigue. However, as the strength of the coupon material increases these modes become increasingly susceptible to various type of EAC. For example, the materials used for ASTM F519 hydrogen embrittlement testing are intentionally very hard (52 to 54 HRC) to ensure they will fail if sufficient hydrogen exposure occurs. Similarly, a recent investigation into unexpected stress corrosion in "low-strength" steel corrosion coupons indicated that high reduction ratios used to achieve the low thickness of the bar material resulted in much higher than expected tensile properties. The importance of knowing and selecting coupons of the right strength and properties will be detailed.