Affiliation:
1. College of Materials Science and Engineering, Tech Institute for Advanced Materials, Nanjing Tech University, Nanjing 211816, China
2. Department of Materials Science and Physics of Metals, Ufa University of Science and Technology, Ufa 450008, Russia
Abstract
In the present study, the stress corrosion cracking (SCC) of ultrafine-grained (UFG) Ti-2Fe-0.1B prepared by equal channel angular pressing (ECAP) was investigated by a slow strain rate test (SSRT) with in-site electrochemical equipment. In comparison with the atmosphere, results indicated that the mechanical properties of Ti-2Fe-0.1B alloy degraded in the simulated sea water, and the SCC sensitivity of UFG Ti-2Fe-0.1B alloy is much lower than the initial coarse-grained (CG) state. The enhanced SCC resistance of UFG Ti-2Fe-0.1B alloy could be attributed to the mechanical and corrosive aspects simultaneously. First of all, the strength of UFG Ti-2Fe-0.1B alloy is much higher than the CG state, but the elongation to failure of UFG Ti-2Fe-0.1B alloy decreased more than 1.8 times. The UFG sample suffered crack initiation until failure with a relative short time and low plastic deformation, which weakened the effect of corrosion during SSRT. In addition, X-ray photoelectron spectroscopy (XPS) revealed that the thickness of the passivation film of the UFG Ti-2Fe-0.1B alloy is thicker and that the component of the passivation film possesses a higher proportion of TiO2 in the same etched depth, which is beneficial to the corrosion resistance. Furthermore, according to the in-site electrochemical experiment curves, it is believed that the passivation film has a higher repair ability after cracking during SSRT for the UFG Ti-2Fe-0.1B alloy due to the decrease in grain size and the increase in dislocation density.
Funder
National Key R&D Program of China
National Natural Science Foundation of China
Russian Science Foundation
Priority Academic Program Development of Jiangsu Higher Education Institutions
Subject
General Materials Science,Metals and Alloys