TITLE:
Effect of Pipe Diameter on Electrochemical Behavior of Stainless Steel Type 304 Pipes in Tap Water
AUTHORS:
Noriyuki Tanaka, Shigeru Sato, Itaru Ikeda, Tadahiko Uchida, Motoki Kuratani, Yutaka Yamada, Osamu Sakurada
KEYWORDS:
Stainless Steel Type 304, Electrochemical Consideration, Pipe Diameter, Electrochemical Behavior, Tap Water
JOURNAL NAME:
Materials Sciences and Applications,
Vol.10 No.11,
November
18,
2019
ABSTRACT: We investigated the effects of pipe diameter on the corrosion resistance of stainless steel type 304 pipes using electrochemical measurements. Compared to plate steel, pipes have harder physical properties and tend to be harder and showed greater permeability with decreasing inner diameter. We found that the maximum corrosion current density in the secondary active state, which is the starting point of secondary passivation, appeared in the polarization curve measurement in tap water. Similar to the Vickers hardness and the maximum current density in the secondary active state, the permeability tended to increase as the diameter decreased. This is thought to increase the amount of deformation-induced martensitic and increase corrosion susceptibility. The peak of the secondary active current density was clearly seen as the potential sweep speed was increased. In addition, potential sweep speed dependence was observed in the corrosion susceptibility evaluation of deformation-induced martensite. In comparison with acid treatment, the formation of deformation-induced martensite was considered to occur in the extreme surface layer. The maximum corrosion current density in the secondary active state is expected to be a new susceptibility evaluation method for evaluating the deformation-induced martensitic transformation.