Research on corrosion and fatigue performance of weathering steel and High-Performance steel for bridges

Abstract

Weathering steel (WS) and high-performance steel (HPS) have been widely used in bridge engineering. Corrosion effects can lead to a reduction in the fatigue strengths of the WS and HPS, especially for the base metals, threatening the safety and reliability of the WS or HPS bridge. Corrosion typically consists of uniform corrosion and pitting corrosion, and the reduction of the fatigue strength of the WS and HPS owing to corrosion generally depends on the steel type and corrosion time. This study conducted an experimental test to investigate the corrosion and fatigue performances of the base metal of Q345CNH, a typical type of WS used in China, and HPS 70 W, a typical steel used in the U.S. First, the corrosion performances of both the WS and HPS under a marine environment were investigated through an accelerated corrosion test. Both the uniform corrosion and pitting corrosion of the specimens during the corrosion tests were found to match well with the proposed uniform corrosion and pitting corrosion numerical model. The simulated corrosive environment was also consistent with Qionghai (C3), a category of marine environment, according to Chinese specifications. Subsequently, to further study the fatigue performance of the corroded WS and HPS, a fatigue test was conducted on the corroded specimens subjected to the various corrosion cycles. The experimental results indicated that the corrosion effect causes a reduction in the fatigue strengths of Q345CNH and HPS 70 W. In general, the corrosion effect causes a 22.6–38.3% reduction in fatigue strength for Q345CNH, and a 31.9–35.7% reduction in fatigue strength for HPS 70 W. Meanwhile, the fatigue cracks of all failed specimens are derived from the pitting flaws. In addition, the reduction of the fatigue strength for both the WS and HPS increases with an increase in corrosion time. Moreover, the fatigue cracks wholly initiate from the pitting flaws. The results on the corrosion and fatigue performance could offer guidance for the design of uncoated WS bridges.