Titanium alloy excellent in intergranular corrosion resistance

Abstract

A titanium alloy contains Ni in a content of 0.35% to 0.55%; Pd in a content of 0.01% to 0.02%; Ru in a content of 0.02% to 0.04%; and Cr in a content of 0.1% to 0.2%, with the remainder including titanium and inevitable impurities, in which the titanium alloy includes nickel-rich phases, each nickel-rich phase being a phase (other than titanium alpha phase) locally containing Ni in a content of 10 times or more the average Ni content of the titanium alloy, the nickel-rich phases are aligned along a rolling direction to form a row, and a multiplicity of the rows are aligned substantially in parallel in a cross direction. The titanium alloy minimizes the proceeding of intergranular corrosion even in specific environments where the intergranular corrosion may easily proceed.

1 . A titanium alloy comprising:
 nickel (Ni) in a content of 0.35 to 0.55 percent by mass (hereinafter contents will be simply expressed in “%”);   palladium (Pd) in a content of 0.01% to 0.02%;   ruthenium (Ru) in a content of 0.02% to 0.04%; and   chromium (Cr) in a content of 0.1% to 0.2%,   with the remainder including titanium and inevitable impurities,   wherein the titanium alloy includes nickel-rich phases, each nickel-rich phase being a phase (other than titanium alpha phase) locally containing Ni in a content of 10 times or more the average Ni content of the titanium alloy, wherein the nickel-rich phases are aligned along a rolling direction to form a row, and wherein a multiplicity of the rows are aligned substantially in parallel in a cross direction.   
     
     
         2 . A titanium alloy comprising:
 Ni in a content of 0.35% to 0.55%;   Pd in a content of 0.01% to 0.02%;   Ru in a content of 0.02% to 0.04%; and   Cr in a content of 0.1% to 0.2%,   with the remainder including titanium and inevitable impurities,   wherein the titanium alloy includes one or more nickel-rich phases, each nickel-rich phase being a phase (other than titanium alpha phase) locally containing Ni in a content of 10 times or more the average Ni content of the titanium alloy, and wherein the nickel-rich phases contain Ti 2 Ni.   
     
     
         3 . The titanium alloy according to one of  claims 1  and  2 , which is obtained by performing final annealing at a temperature in the range of 600° C. to 725° C. after rolling.