Analysis on Galvanic Corrosion Behavior of TA2, BAl7-7-2-2 and 921A

Galvanic corrosion behaviors of titanium alloy TA2, nickel aluminum bronze alloy BAl7-7-2-2 and ship hull steel 921 A in 3.5% Na Cl solution were investigated. The corrosion potential differences of 921A/TA2 and 921A/BAl7-7-2-2 were 713.5mV and 412mV respectively, with 912 A as anode. For the same couple, the current and corrosion rate of the couple with area ratio of 10:1 was much higher than those of the couple with area ratio of 1:1. For the couple of the same area ratio, the current and corrosion rate of the couple of 921A/BAl7-7-2-2 was higher than those of the couple of 921A/TA2. The BAI7-7-2-2/921 A couple and TA2/921 couple with area ratio of 10:1 have higher galvanic coefficients. Insulation protection should be used to connect TA2 and BAl7-7-2-2 with 912 A steel. By comparison, it is found that the corrosion potential difference of 921A/TA2 is higher, but corrosion rate and galvanic corrosion coefficient of 921A/BAl7-7-2-2 is higher than 921A/TA2.