Improved Corrosion and Wear Resistance of a Niobium Alloyed Co-Cr-Mo Alloy

摘要

Co-Cr-W alloys, such as UNS R30006, have long been served in various industries for high-temperature corrosion and wear applications. The Co-Cr-Mo alloys have also been developed to meet the market requirements for improved corrosion resistance with similar wear resistance as of Co-Cr-W alloys, especially for oil and gas, and power generation industries. The corrosion and wear resistance of a niobium (Nb) alloyed Co-based Co-Cr-Mo alloy (Co24Cr12Mo2Nb) is studied in this work. In addition, alloys UNS R30006 and UNS R30021 are tested for comparison. According to ASTM G59, potentiodynamic polarization test is conducted in 3.5 wt% sodium chloride (NaCl) solution. The immersion test is conducted in acidified 6% ferric chloride solution and green death solution by following ASTM G48. The critical pitting temperatures of these alloys are detected in both test solutions. Wear testing is conducted according to ASTM G65 (abrasion), ASTM G98 (galling), ASTM G76 (erosion) and ASTM G99 (metal on metal wear). Test data suggest that the Nb alloyed Co-Cr-Mo alloy possesses improved corrosion resistance compared to alloy R30006 with similar wear properties, and improved wear resistance compared to alloy R30021 with similar corrosion properties.