Failure Analysis on Corrosion of 316 Stainless Steel Guardrail

Corrosion failure occurred about two months after installation of 316 stainless steel guardrail in a neighborhood near the seaside. The causes of corrosion failure of guardrail were analyzed by means of chemical composition analysis, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that there were obvious the chemical composition differences between guardrail weld seam area and base metal, which led to a large electrode potential difference between them, and there was a certain welding residual stress at the weld seam. Moreover, the installation location was near the seaside, and the air humidity was high, the electrochemical corrosion and stress corrosion occurred in the weld seam deposited metal area of the guardrail. Under the combined action of the two kinds of corrosion, the guardrail corrosion failure was caused.