PURPOSE: To improve the corrosion resistance of a marine diesel engine exhaust valve by controlling iron content, in an Ni alloy of specific composition containing Cr and other elements, to a specific value or below.

CONSTITUTION: This exhaust valve alloy has a composition consisting of, by weight, 0.02-0.07% C, 24-32% Cr, 0.7-3.0% Ti, 0.7-1.5% Al, 0.7-1.5% Nb, 0-0.1% Zr, 0-0.006% B, 0-1% Fe, and the balance Ni. It is necessary to regulate Fe content in this alloy to ≤ about 1%, in contrast to many instructions given by the conventional techniques, in order to produce excellent corrosion resistance at a temp. exceeding 700°C. This alloy has resistance to the product of combustion, to meet with, of a representative grade of fuel in a ship atmosphere. Moreover, superior tensile characteristics can be produced when Cr content is 24-28%.