Highly corrosion resistance alloys (HCRAs) are becoming more popular for oilfield
applications, where not only corrosion resistance is important, but also mechanical integrity
and long term reliability. These materials are often exposed to a wide variety of aggressive
environments that can range from marine splash zone to down-hole sour environments. The
fabrication of these HCRAs metallic coatings typically involves coating low grade carbon steels
with one or different layers of the HCRAs using techniques such as thermal spray coating,
chemical vapor deposition, weld overlay, electrodeposition, etc. Previous work by the authors
has described a novel testing methodology, based on the zero resistance amperometry (ZRA),
which allows the determination of the critical pitting temperature (CPT) as well as the critical
crevice temperature (CCT) in small angular sectioned samples taken from actual production
hydraulic cylinders. In this paper, the CPT and CCT measurements that were successfully
employed for evaluating UNS N06625 weld overlay materials compared with two potential
HCRAs coated steels (UNS R31233 and UNS W73021). The main objective was to develop a
rapid approach for the relative ranking of these materials for aggressive offshore applications.
From the results obtained in this work, it is expected that the UNS W73021 weld overlay
should have relatively better performance than the UNS N06625 weld overlays, which is
expected to have relatively better performance than the R31233 weld overlays.
Keywords: critical pitting temperature, critical crevice temperature, corrosion resistance alloy,
weld overlay, UNS N00625, UNS R31233, UNS W73021