Galvanic Corrosion among Ti6Al4V ELI Alloy, CoCrMo Alloy, 316L-Type Stainless Steel, and Zr1Mo Alloy for Orthopedic Implants

In orthopedics, occasionally, different types of metals are used in applications in which they are in contact with each other. However, few studies have electrochemically investigated the galvanic corrosion of orthopedic implants formed of different metals. In this study, galvanic corrosion of Ti6Al4V ELI alloy, CoCrMo alloy, and 316L type stainless steel, which are used in orthopedics, and a newly developed Zr1Mo alloy as a low-magnetic susceptibility material was evaluated in saline. Coupling of the Ti6Al4V ELI and CoCrMo alloys did not exhibit localized corrosion and maintained highly stable passive films. Coupling of the 316L type stainless steel and CoCrMo alloy, temporary localized corrosion occurred. Similarly, coupling of the Zr1Mo and CoCrMo alloys, temporary localized corrosion occurred. However, both of 316L type stainless steel and Zr1Mo alloy were finally repassivated spontaneously with the immersion time. The degree of the localized corrosion of the Zr1Mo alloy was smaller than that of 316L type stainless steel. No galvanic current was observed when the Ti6Al4V ELI and CoCrMo alloys were coupled. A slight galvanic current flowed when 316L type stainless steel or the Zr1Mo alloy was coupled with the other alloys; however, the galvanic current with the Zr1Mo alloy coupling recovered to zero after a certain period owing to repassivation. No metal ions were detected from the couplings with Zr1Mo. [doi:10.2320/matertrans.MT-MLA2022001]