Electrochemical Evaluation of the Effect of Heat Treatment and Stress on the Corrosion Characteristics of 7050 Aluminum in 3.5% NaCl Solution

摘要

Potentiodynamic polarization curves have been used to evaluate (in a survey mode) the effect of heat treatment and stress on the corrosion behavior of 7050-XX aluminum in deaerated 3.5% NaCl solutions. Specimens, which were machined from extruded ring material, were examined in the as-received condition and following heat treatment at 580 exp 0 F for 0.5 min. The stress levels used in this study ranged from 40 to 90% of the 0.2% offset yield strength. Results indicate that within this stress range, using the given experimental method, medium, and timescales, that there is no significant trend for the effect of stress on the electrochemical-corrosion behavior for the materials examined. The heat-treated specimens have lower uniform corrosion rates than the as-received forms, but are more susceptible to pitting. However, pitting is not spontaneous for either material in this environment. In addition to investigating the variables of stress and heat treatment, we have also compared the behavior of specimens machined from three different orientations within extruded ring material. Generally, the longitudinal and circumferentially oriented specimens were more similar electrochemically than specimens obtained from the radial orientation. The radial specimens generally showed lower uniform corrosion rates and appeared to be less susceptible to pitting. (ERA citation 11:007463)