Corrosion Behavior of Welded Joint of Q690 with CMT Twin

Abstract

Low alloy steel of Q690 was welded with the method of CMT Twin. The corrosion behavior of welded joint had been investigated using scanning vibrating electrode technique (SVET) in 3.5% NaCl solution. The research results showed that the appearance of the troostite increased the hardness of the heat affected zone. Furthermore, the corrosion products of different microstructure were identical, and the white products (Fe(OH)2) of welded joint turned into products of rufous (Fe(OH)3). The quantitative information provided by SVET was discussed, and the corrosion degree was measured by some parameters. In comparison with other areas, the corrosion rates of the overheated zone and the base metal were higher. Then, the corrosion resistance of the weld zone with CMT Twin was greatly improved, when compared with that of the base metal. Therefore, Ni has significant influence on corrosion resistance of weld zone. In summary, it can be discovered that the corrosion rates of various zones were related to the welding heat input.