Deterioration of Mechanical Properties Steel Plate Due to Corrosion Phenomena-the Statistical Surveys of Full-Scale Ship and Electrochemical Model-Based Establishment

Abstract

The mechanical properties of the corroded steel plates are important in analyzing the remaining capacity of ship structures. However, the data is scarce and most of that came from the simulated test with physical processing. In this study, the mechanical properties of the corroded steel plate from the real ship were investigated. Moreover, the mechanical properties declines model was constructed by conducting the tensile testing on the localized corroded and general corroded steel plate which were created by using the impressed-current method and corrected by the data from the real ships. The preliminary results showed that the young’s modulus, yielding strength, tensile strength and extension rate remains constant on the general corroded steel plates which have a reduced thickness from 5% to 35%. In localized corrosion, however, the extension rate decreases rapidly in prophase, and then the tensile strength decreases and the yielding plateau disappears. Also, the Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) results revealed that the microstructures of the corroded steel plate from the real ship and simulated experiment are all same as the new plate, proving that the alternations of mechanical properties are the result from the corrosion-induced stress concentration.