ABSTRACT
In the oil and gas industry, key components made of carbon steels are exposed to severe corrosion environments in which high partial pressures of H2S, CO2 and Cl exist. This study explores the possibility whether applying a Corrosion Resistant Alloy (CRA) coating on carbon steels can protect them from the corrosive environment. UNS N10276 was used as the source material and deposited on UNS G41400 carbon steel coupons using a Plasma Enhanced Magnetron Sputter (PEMS) process developed at Southwest Research Institute (SwRI). The coating thickness was varied from 0.1 to 11 µm. The coated coupons, along with uncoated ones, were then tested under a NACE MR0175 / ISO 15156 Level V condition. Preliminary results indicate that the baseline UNS G41400 samples (with no UNS N10276 coating) had a corrosion rate of 15.44 mpy (0.392 mmpy) after exposure and many pits were observed on the sample surface. The maximum pit depth was 0.71 mils (0.018 mm). In contrast, under the optimal coating conditions, the UNS N10276 coated samples showed the mass loss corrosion rates of <0.5 mpy (0.0127 mmpy), and exhibited no pitting. These preliminary results indicate that the approach of using a CRA coating on carbon steel can indeed retain the strength of the base metal while greatly improving the corrosion resistance. In this paper, the PEMS process will be discussed and the detailed corrosion test conditions and the corrosion data will be presented.
