Corrosion failure analysis of engineering structural steels in tropical marine atmospheres: A comparative study of ordinary and new weathering steels

Abstract

Reliable applications for weathering steels face challenges in harsh tropical marine atmospheric environments. The development of new weather steel suitable for tropical marine atmospheric environments is of great significance. In the paper, the corrosion failure behavior of ordinary and newly designed weathering steels exposed to tropical marine environments for two years was studied by employing various analytical methods. The results indicate that the extensive formation of akaganeite and lepidocrocite occurs deep inside the abnormally thick corrosion products of ordinary weathering steel with the accumulation of Cl−, which is laborious to be affected by the rinsing effect of rainfall. Based on the study of the composition, phase, and structure of abnormally thick corrosion products, a chain evolution mechanism of corrosion failure is proposed. By optimizing the content of Cu, Mo, and Ni, the newly designed weathering steel can effectively suppress the chain failure process and increase the corrosion resistance by approximately doubling. On the whole, the newly designed weathering steel can be well applied to tropical marine atmospheric environments.