Abstract: Regularity of the initial atmospheric corrosion of A3 steel in the presence of NaCl was investigated. The results showed that NaCl can accelerate the corrosion of A3 steel. Dry mass gain of A3 steel in the presence of NaCl deposition increases with the exposure time, which can be correlated by using exponential decay function. The relationship between dry mass gain and amount of NaCl deposition at a certain exposure time follows a quadratic function. More amount of NaCl deposition will slow down the corrosion rate to some extent after exposure for a certain time. SEM/EDAX was used to characterize the corrosion surface and products. The surfaces of the NaCl treated A3 steel were obviously uneven, and some tiny crevices appear in the corrosion products that could help O2 transmit to the inner layer. The amount of oxygen in atomic percentage in the corrosion products increases with the amount of NaCl deposition.

Key words: A3 steel, Atmospheric corrosion, Corrosion, NaCl