In this study, the pre-corroded experiment procedure can be devised as four main steps: 1) the  pure NaCl crystals of 50 g were weighed by an electronic balance and poured into one liter of  deionized water and stirred with glass rod at an ambient temperature of (25 ± 1 °C) for 5 min; 2)  four groups of numbered samples were alternately immersed in 5% NaCl solution at an ambient  temperature of (25 ± 1 °C) for 0 h, 24 h, 48 h, and 96 h, respectively; 3) the corrosion products were  removed by membrane removal solution (prepared with 100 mL HCl, 100 mL deionized water and  0.6 g C6H12N4); 4) all surfaces of samples were rinsed with deionized water and dried by a blower  for pit depth measurement.