RETRACTED: Mechanical properties and corrosion resistance of low-alloy steels in atmospheric conditions containing chloride

Abstract

The corrosion resistance (weight loss) and mechanical properties (i.e., yield strength, ultimate tensile strength, and elongation) of four newly developed low-alloy steels (LAS) were compared with a weathering steel (Acr-Ten A) and a carbon steel (SS400) using a laboratoryaccelerated test that involved cyclic wet/dry conditions in a chloride environment (5 wt.% NaCl). The new LAS were designated 1604A, 1604B, 1605A, and 1605B. After 72 cycles of cyclic corrosion tests, the change in mechanical properties by corrosion was the least for SS400, Acr-Ten A was second, and effects of corrosion on the mechanical properties of the other four low-alloy steels were similar. The susceptibility of the steels to corrosion based on their weight loss was the most for SS400, and the least for 1605A and 1605B. In addition, it was found that the corrosion potentials of low-alloy steels are more active prior to accelerated corrosion tests than after the accelerated test, and the corrosion tendency of the six steels immersed in 3.5 wt.% NaCl solutions after 72 cycles of accelerated corrosion tests was the least for 1605A and 1605B because the corrosion potentials were higher than other steels. The rust characteristics observed by SEM and analyzed by FTIR and EPMA indicated that most of the rust layers on the test steels were composed of a loose outer rust layer and a dense inner rust layer. The outer rust layer of each steel was composed of -FeOOH,-FeOOH, magnetite (Fe3O4), H2O, and amorphous ferric oxyhydroxide (FeOx(OH)3 − 2x, x = 0 to 1), while the inner rust layer was composed mainly of Fe3O4 with a little -FeOOH. In addition, it was apparent that the copper and chromium alloying additions were enriched, respectively, at the rust-layer/substrate interface and in the rust layers. Finally, combining the results of the accelerated tests, the rust layer analysis, and the corrosion potential measurements showed that low-alloy steels, such as 1605A and 1605B, have better weathering steel properties than Acr-Ten A for use in the humid and salty weather. © 2005 Elsevier B.V. All rights reserved.