Influence of effective strain on the corrosion behavior of nickel-based GH4710 superalloy in chloride solutions

Abstract

The influence of effective strains with a range from 1.1 to 2 on the corrosion resistance of GH4710 superalloy in chloride solutions was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky. The electron backscatter diffraction (EBSD) tests and scanning electron microscopy (SEM) tests were carried out to study the effects of effective strains on the microstructure evolution of GH4710 superalloy, which were treated by means of hot compression at 1120 ℃ with a strain rate of 0.1 s−1. With the increasing strain, the microstructure results revealed that the proportion of deformed structures containing high-density dislocations and sub-grain boundaries decreases as well as the volume fraction of dynamic recrystallization (DRX) grains increases. The lattice distortion of DRX grains with finer and more uniform was smaller compared with the original coarse deformed grains. Corrosion pits preferentially initiated at the grain boundaries of original coarse deformed grains with large lattice distortion. The proportion of low coincidence site lattice (CSL) grain boundaries increased with the increase of strain, which can effectively optimize the grain boundary structure and improve the corrosion resistance. The corrosion behavior of GH4710 superalloy with different effective strains was closely related to grain boundary characters and microstructure.