Resistance to Forms of Corrosive Attack

Cobalt is susceptible to pitting and crevice corrosion, and is usually very resistant to SCC in many environments, but at higher temperatures (>150 °C) in acid chlorides and strong bases it may experience stress corrosion cracking. Cobalt based alloys have an excellent resistance to erosion corrosion, especially from cavitation, and they also typically have outstanding resistance to high temperature corrosion. The resistance of cobalt alloys to oxidation and carburization at high temperatures is generally very good, and the resistance to sulfidation is better than that of nickel-based alloys. Furthermore, cobalt-based alloys tend to be more resistant to hydrogen embrittlement compared to their nickel counterparts.