Pitting Morphologies and Characteristics of Low-Alloy Steel With and Without Plastic Deformation in Industrial and Non-i

  • PDF / 7,350,343 Bytes
  • 12 Pages / 593.972 x 792 pts Page_size
  • 9 Downloads / 160 Views

DOWNLOAD

REPORT


JMEPEG (2020) 29:8294–8305 https://doi.org/10.1007/s11665-020-05276-w

Pitting Morphologies and Characteristics of Low-Alloy Steel With and Without Plastic Deformation in Industrial and Non-industrial Marine Splash Zones Mindong Chen, Kun Pang, Yang Wang, Xize Liu, and Fan Zhang Submitted: 4 June 2020 / Revised: 5 October 2020 / Accepted: 11 October 2020 / Published online: 16 November 2020 Pitting morphologies of E690 low-alloy steel in industrial and non-industrial marine splash zones are statistically analyzed, including the influence of plastic deformation. Results show that in a marine splash zone, E690 low-alloy steel experiences severe uniform corrosion and pitting corrosion, and the corrosion is more severe in the high-temperature non-industrial environment. The relationship between the pitting area changes and the depth can be well fitted to the Boltzmann cumulative distribution function to investigate the corrosion factors. In non-industrial marine splash zone, high content of chloride ions makes the metal surface have a high roughness and anodic dissolution is then promoted. The pitting depth is strongly promoted by anodic dissolution. In the marine splash zone, plastic deformation aggravates the maximum pitting depth, especially in the initial stage and in SO2-pollutant environments, although this effect gradually decreases. Pitting on low plastic deformation area in U bend samples may influenced by receiving electrons, which inhibits the protective FeOOH generation. Keywords

carbon steel, dimensionality reduction, marine environment, plastic deformation, sulfur dioxide

1. Introduction With the development of the marine economy and new steel materials, many high-strength low-alloy steels are used in marine engineering. Therefore, studying the corrosion of these steels in practical processes has become very important (Ref1, 2). The splash zone is the most corrosive region for steels. The main forms of low-alloy steel corrosion in the marine splash zone include ulcer-like corrosion (Ref 3), pitting corrosion (Ref 4), and stress corrosion (Ref 2, 3, 5). Among these, pitting corrosion is the most common. Marine splash zones are exposed to complex environmental factors (Ref 3), including dry-wet cycles (Ref 6, 7), and seawater electrolyte films (Ref 8). These factors form a complex multi-layered rust layer (Ref 9, 10), which makes it difficult to distinguish the macroscopic pitting morphology. The scale of marine engineering is growing rapidly, but research on marine engineering safety and assessment (Ref 11) based on Mindong Chen, SINOPEC Research Institute of Safety Engineering, Qingdao 266100, PeopleÕs Republic of China; State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, PeopleÕs Republic of China; and SINOPEC Jinling Company, Nanjing 210033, PeopleÕs Republic of China; Kun Pang and Fan Zhang, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, PeopleÕs Republic of China; Yang