Corrosion mechanisms of a new-type high-manganese austenitic alloy in a molten zinc bath

A new-type high-manganese austenitic alloy for immersed rolls in continuous hot-dip coating lines was developed.The corrosion behaviors of the high-manganese austenitic alloy in molten zinc at 490℃ were systematically studied in order to better understand the reaction mechanism.The results indicated that the high-manganese austenitic alloy showed a better corrosion resistance than 316 L stainless steel.Its corrosion rate in molten zinc was calculated to be approximately 6.42×10^-4 g·cm^-2·h^-1,but 1.54×10^-3 g·cm^-2·h^-1 for 316 L stainless steel.The ultimate corrosive products of the high-manganese austenitic alloy were Γ,δ and ζ phases,while that of 316 L stainless steel was almost ζ phase.δ phase in the high-manganese austenitic alloy contains about 8.5% Cr,and the existence of Cr improves the stabilization of δ phase.This δ phase with enrichment of Cr acts as a barrier slowing down the reaction of Fe and Zn,and improves the corrosion resistance of the high-manganese austenitic alloy.Substituting manganese for nickel to manufacture a high-manganese austenitic alloy of low cost is feasible.