Fatigue Behavior and Fracture Surface Analysis of Corroded High-Strength Bridge Cable Wires

Area of Science:

• Materials Science
• Corrosion Engineering
• Structural Integrity

Background:

• Bridge cable wires are susceptible to fatigue failure from stress and environmental degradation.
• Existing galvanized coatings may not provide sufficient long-term protection.
• Understanding corrosion effects on mechanical properties is crucial for infrastructure longevity.

Purpose of the Study:

• To investigate the fatigue and mechanical behavior of corroded bridge cable wires with zinc-aluminum (Zn-Al) alloy coatings.
• To compare the corrosion resistance of Zn-Al alloy coatings with traditional galvanized coatings.
• To quantify the impact of corrosion on the fatigue life and mechanical properties of steel wires.

Main Methods:

• Salt spray corrosion tests to evaluate coating performance.
• Microstructure analysis to understand corrosion mechanisms.
• Tensile and fatigue tests on corroded and uncorroded wires.
• Fracture surface analysis using graphical contour recognition.

Main Results:

• Zn-Al alloy coating demonstrated superior corrosion fatigue resistance due to improved toughness and protective phase formation.
• Accelerated corrosion models predict a service life of 29.1 years for 70 μm Zn-Al coatings.
• Corrosion significantly reduces fatigue properties, particularly ductility, with pit depth logarithmically weakening fatigue life.
• Multiple corrosion pits act as fatigue sources, drastically reducing wire lifespan.

Conclusions:

• Zn-Al alloy coatings offer enhanced protection against corrosion fatigue for bridge cables.
• Corrosion-induced material embrittlement and reduced fracture toughness are key factors in fatigue life reduction.
• The number and distribution of corrosion pits critically influence fatigue failure modes and overall wire durability.