Corrosion morphology characteristics and time-varying evolution of corrosion pits of Q690 high strength steel

Abstract

Due to exposure to harsh environments, steel structures are susceptible to corrosion, resulting in a significant reduction in their normal service life and increasingly prominent durability issues. To achieve this, humid-hot cycle and immersion accelerated corrosion tests were conducted. Laser confocal microscopy was utilized to measure surface coordinate parameters, enabling an examination of variations in surface roughness parameters and corrosion pit size over the course of corrosion time. The research findings indicate that during the initial phase of corrosion, a limited number of needle-like pitting products are formed, resulting in relatively mild damage. However, as the corrosion time progresses, the metallic luster diminishes rapidly, and the surface pitting micro-morphology of the specimen gradually transforms into corrosion pits. Microscopic scanning analysis reveals that the corrosion behavior extends rapidly along the horizontal direction, eventually completely enveloping the surface of the specimen, and the accumulation of surface products provides significant protection to the interior of the matrix. Furthermore, using the loss ratio can better analyze the errors that exist in the actual testing process, in order to accurately reflect the corrosion damage evolution law of HSS.