AÇO ESTRUTURAL COM RESISTÊNCIA À CORROSÃO ATMOSFÉRICA MARINHA SEVERA E DE ELEVADA RESISTÊNCIA MECÂNICA

A Ni-Si-Mo structural steel was developed with yield strength above 480 MPa and high atmospheric corrosion resistance. The high yield strength enables the thickness reduction of metallic components and, consequently, the weight of the whole structure, including masonry. The corrosion resistance was measured by field tests with intermittent sprinkling of 3% w/v NaCl salt solution three times a week (ISO 11474) during three years and exposure to marine atmosphere (NBR 6209) during six years, compared with USI-SAC 300 (weathering steel) and SAE 1006 steels. The Ni-Si-Mo steel shows the best performance and its oxide layer does not scale off. According to these results, it is possible to recommend the use of the unpainted Ni-Si-Mo steel in environments where the traditional weathering steels usually requires painting. In this way, all costs involved with maintenance, repair and eventual shutdowns can be eliminated, as well as occasional problems such as contamination and poor access to the site.