Effect of pitting corrosion in NaCl solutions on the statistics of fracture of beryllium

Abstract

The effect of pitting corrosion, occurring in NaCl solutions, on the bending behavior of commercial beryllium was studied. Three concentrations of NaCl solutions (0.01, 0.1, and 1 M) were used in the experiments. Bend specimens were exposed to these solutions for a total of 168 hours. Weibull statistics were used to analyze the experimental bend-strength data and were applied to the failure strength, displacement to failure, and yield strength. Samples exposed to the 1 M NaCl solution exhibited a high Weibull modulus, with a higher retained mean failure strength and displacement to failure. On the other hand, the samples exposed to the 0.01 and 0.1 M NaCl solution exhibited significantly lower mechanical property values and Weibull moduli, accompanied by a larger scatter in the failure strength and displacement to failure. The engineering yield strength of the samples did not change significantly with exposure to the NaCl solutions, although there was an increase in the scatter of the values. These effects on the mechanical properties were attributed to a decreasing propensity for the formation of localized deep pits and an increasing propensity for uniform shallow pitting with increasing NaCl concentrations. Scanning electron microscopy (SEM) was primarily used for quantifying these corrosion pitting effects. In addition, atomic-force microscopy (AFM) and potentiodynamic polarization experiments were also conducted to provide supportive evidence for the differences in the pitting behavior of the beryllium with different NaCl concentrations.