Friction and wear characterization of some cobalt- and iron-based superalloys in zinc alloy baths

A full-journal submerged bearing test rig was built to evaluate the friction and wear behavior of materials in zinc alloy baths. Some cobalt- and iron-based superalloys were tested using this rig at conditions similar to those of a continuous galvanizing operation (load and bath chemistry). Metallographic and chemical analyses were conducted on tested samples to characterize the wear. It was found that a commonly used cobalt-based material (Stellite #6) not only suffered considerable wear but also reacted with zinc baths to form intermetallic compounds. Other cobalt- and iron-based superalloys appeared to have negligible reaction with the zinc baths in the short-term tests, but cracks developed in the sub-surface, suggesting that the materials mainly experienced surface fatigue wear. The commonly used cobalt-based superalloy mostly experienced abrasive wear.