CAJ | 학술논문

The corrosion behaviors of extrusion, under-aged, peaked-aged and over-aged WE93 alloys in NaHSO3 solutions were in-vestigated by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The weight loss rates, corrosion morphologies and polarization curves were analyzed. The peak-aged specimen in NaHSO3 salt spray had the highest corro-sion rate of 0.9787 mg/cm2/d, while extrusion specimen led to the lowest of 0.2184 mg/cm2/d. The specimens could be arranged in decreasing order of corrosion rates:extrusion<under-aged<over-aged<peak-aged. Polarization curves also gave effective evaluation of corrosion rates in agreement. The NaHSO3 played a great role in the corrosion behaviors of WE93 alloys. The main reasons were that HSO3–developed a reaction:O2+2HSO3–+2e→2HSO42–→2H++2SO42–to generate H+, accelerating the process of corrosion re-action. SO42–stimulated corrosion and led to an autocatalytic type of reaction:Mg2++SO42–+7H2O→MgSO4–7H2O. XRD character-ized that Mg(OH)2 and MgSO4·7H2O were the main corrosion products.