This investigation studies the influence of refinement of the cast grains on the mechanical properties of nickel base superalloys (713LC, MAR-M-246 and C1O3). The purpose was to improve the service life of T-63 rotors which now have their service life limited by fatigue in the rim sections. The rotor is presently produced from MAR-M-246 by a vacuum investment casting process. The conventional casting techniques employed in its manufacture result in large columnar grains which cause an anisotropic fatigue behavior. The grain refining technique developed consisted of adding 0.12B to the melt and establishing the proper time-temperature cycles so that substrates for effective heterogeneous nucleation were available for grain refinement of the different section sizes in the T-63 rotor. The mechanical properties investigated included tensile properties. low-cycle fatigue resistance, combined fatigue-creep lives, thermal fatigue and oxidation properties, and stress rupture behavior were determined for the unrefined, fine columnar, and refined equiaxed structures of the three test alloys. The grain refinement improved the low-cycle fatigue performance of 713LC and MAR-M-246 alloys; the fatigue behavior of C103 was not affected. Grain refinement increased the yield strength and decreased the tensile strength of 713LC and MAR-M-246. The strength of C103 was decreased.
Grain refinement of cast nickel-base superalloys and its effect on properties
Kornfeinung in Nickelguss-Superlegierungen und ihr Einfluss auf die mechanischen Eigenschaften
1982
38 Seiten, 26 Bilder, 10 Tabellen, 54 Quellen
Conference paper
English
Grain structure control of nickel-base superalloys in casting process: effect of melt additions
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