High Ni corrosion resistant alloy with excellent intergranular corrosion resistance and pitting corrosion resistance as well as hot workability and cold workability.

摘要

PROBLEM TO BE SOLVED: To provide a high Ni alloy which has dramatically improved intergranular corrosion resistance and also has improved pitting corrosion resistance in consideration of a use environment, and which is excellent in hot workability and cold workability. SOLUTION: In mass %, C: 0.001 to 0.050%, Si: 0.01 to 1.50%, Mn: 0.01 to 1.50%, S: ≦0.050%, Ni : 30.0 to 50.0%, Cr: 18.5 to 25.0%, Mo: 2.00 to 5.00%, Cu: 1.00 to 5.00%, Al: 0.01 to 0 .50%, Ti: 0.5 to 2.0%, N: 0.0001 to 0.0500%, Fe: ≧20.0% alloying elements, and unavoidable impurities, and has a pitting corrosion resistance PRE. Value=[%Cr]+3.3[%Mo]+16[%N]:≧31.5... The Ni alloy of the formula (1), which is the outer surface of the alloy rod or alloy tube made of the Ni alloy. A high Ni alloy excellent in intergranular corrosion resistance and pitting corrosion resistance as well as hot workability and cold workability, in which the ratio of the crystal grain size to the crystal grain size in the middle part is ≧1.5. [Selection diagram] None