Analyses of Corrosion Failure of N80 Water Injection Tubing

A failed surface nitrided N80 water injection tubing was analyzed through microstructure examination and X-ray diffraction(XRD).The results showed that the corrosion products were Fe3O4 and FeOOH.There were a lot of non-metallic inclusions and banded structure in the metal adjacent to the inner surface of the tubing,and rough surface of the internal wall resulted in a discontinuous nitriding layer.Those might be the main reasons of the tubing corrosion.A mass of Cl- in the contaminated well water also accelerated the corrosion of the tubing.