Corrosion Behavior of Typical Engineering Structural Steels in a Plateau Valley Atmospheric Environment

Area of Science:

• Materials Science
• Corrosion Engineering
• Environmental Science

Background:

• Atmospheric corrosion of engineering structural steels is a critical concern.
• The unique plateau valley environment of the Sichuan-Tibet region presents distinct corrosive challenges.
• Understanding steel behavior under stress in this environment is vital for infrastructure durability.

Purpose of the Study:

• To systematically investigate the atmospheric corrosion behavior of Q235, Q420, and Q420qENH steels.
• To evaluate the influence of tensile stress on corrosion mechanisms.
• To identify factors contributing to localized corrosion, such as pitting.

Main Methods:

• Field exposure tests, including uniform and stress corrosion coupon tests.
• Electrochemical measurements for corrosion rate assessment.
• Microscopic characterization to analyze corrosion products and morphology.

Main Results:

• All three steels exhibited predominantly uniform corrosion with accompanying pitting corrosion.
• Q420qENH steel demonstrated superior corrosion resistance compared to Q235 and Q420 steels.
• Tensile stress significantly increased uniform corrosion rates and pit dimensions.
• Sulfur enrichment at pit bottoms indicated SO2 involvement in localized corrosion.

Conclusions:

• Q420qENH's enhanced corrosion resistance is attributed to its denser rust layer and composition.
• Tensile stress accelerates both uniform and localized corrosion in these steels.
• Atmospheric SO2 plays a role in aggravating localized corrosion by affecting the rust layer and pit environment.