Sulfidation Resistance of Several Weld Overlay Alloys in A Reducing, Sulfidizing Environment

摘要

Sulfidation has been a frequently encountered high-temperature corrosion issue in petroleum refinery processing. Corrosion-resistant claddings and weld overlays have been widely used to provide protection of refinery equipments against sulfidation attack. Current study examines the sulfidation resistance of weld overlays of austenitic stainless steel Type 309L (UNS S30983), duplex stainless steel Type 312 (UNS S31380), Fe-Cr-Ni alloy 33 (UNS R20033), and Ni-base alloys 622 (UNS N06022) and 72M (UNS N06073) in a highly reducing, sulfidizing environment. Tests were conducted for 2000 hours at 500 °C (932 ℉) in a nitrogen gas environment containing 10% CO, 5% CO_2, 2% H_2O and 0.12% H_2S (vol. %). Results are presented in terms of weight changes, metal loss, and corrosion scale analyses using both optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS).