Accelerated Corrosion and Embrittlement of High-Strength Bridge Wire

Suspension bridge cable inspections have revealed severely corroded and broken wires in some main cables. Accelerated, cyclic corrosion studies were conducted to assess the relative effect of general corrosion, corrosion cracking, and hydrogen embrittlement on the deterioration in material properties of high-strength steel bridge wire. Galvanized and ungalvanized wire samples were corroded in a cabinet that cyclically applied an acidic salt spray, dry conditions, and 100% relative humidity at elevated temperatures. Specimens under zero applied load, and under tensile loads of up to 22 kN (5,000 lb) were studied. Mass loss, hydrogen concentration, ultimate load, and elongation at failure were obtained from corroded and uncorroded samples. Elongation measurements indicate a significant embrittlement of the wires, a result supported by fracture surface morphology. Ultimate load was found to degrade at a rate in excess of that attributable to material loss by general corrosion. The hydrogen content of corroded wire was found to be greater than that of uncorroded wire, particularly for galvanized wire.