| 摘要 |
PROBLEM TO BE SOLVED: To form a homogeneous and stable structure having a high creep strength, a fatigue strength and a good aging resistance by soaking a worked body composed of a nickel base superalloy and thereafter executing heating treatment in multistages under specified conditions. SOLUTION: A worked body composed of a nickel base superalloy is soaked at 850 to 1100 deg.C at least for 2hr under reduced stress. Next, it is heated to 1200 deg.C at a heating rate of about 2 to 20 deg.C/min. Then, it is heated at 1200 to 1300 deg.C at a heating rate of <1 deg.C/min, and a dislocation network therein is eliminated beforeγ' phases dissolve. Successively, it is subjected to heat treatment in the range of 1300 to 1315 deg.C to uniformize untreated castγ' phases together with 1 to 4 volume % of residual eutectic crystals. As the nickel base superalloy, e.g. the one composed of, by weight, 9.3 to 10.0% Co, 6.4 to 6.8% Cr, 0.5 to 0.7% Mo, 6.2 to 6.6% W, 6.3 to 6.7% Ta, 5.45 to 5.75% Al, 0.8 to 1.2% Ti, 0.07 to 0.12% Hf, 2.8 to 3.2% Re, and the balance Ni is used.
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