Patent ID: 8501086

Claim:
A Ni based alloy, which consists of by mass percent, C: not more than 0.03%, Si: 0.01 to 0.5%, Mn: 0.01 to 1.0%, P: not more than 0.03%, S: not more than 0.01%, Cr: not less than 20% to less than 30%, Ni: more than 40% to less than 50%, Cu: more than 3.0% to not more than 5.0%, Mo: 5.0 to 10%, Al: 0.005 to 0.5%, W: 3.77 to 10%, and N: more than 0.02% to not more than 0.3%, with the balance being Fe and impurities, and the following expression (1) is satisfied; 0.5Cu+Mo≧7.0 (1) wherein each element symbol in the expression (1) represents the content by mass percent of the element concerned.