EFFECT OF PITTING CORROSION IN NACL SOLUTIONS ON THE STATISTICS OF FRACTURE OF BERYLLIUM

The effect of pitting corrosion, occurring in NaCl solutions, on the b ending behavior of commercial beryllium was studied. Three concentrati ons of NaCl solutions (0.01, 0.1, and 1 M) were used in the experiment s. Bend specimens were exposed to these solutions for a total of 168 h ours. Weibull statistics were used to analyze the experimental bend-st rength data and were applied to the failure strength, displacement to failure, and yield strength. Samples exposed to the I 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 e xposed to the 0.01 and 0.1 M NaCl solution exhibited significantly low er mechanical property values and Weibull moduli, accompanied by a lar ger scatter in the failure strength and displacement to failure. The e ngineering 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 local ized deep pits and an increasing propensity for uniform shallow pittin g with increasing NaCl concentrations. Scanning electron microscopy (S EM) was primarily used for quantifying these corrosion pitting effects . In addition, atomic-force microscopy (AFM) and potentiodynamic polar ization experiments were also conducted to provide supportive evidence for the differences in the pitting behavior of the beryilium with dif ferent NaCl concentrations.