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Accession Number:
ADA171480
Title:
High Temperature Monotonic and Cyclic Deformation in a Directionally Solidified Nickel-Base Superalloy.
Descriptive Note:
Contractor rept.,
Corporate Author:
GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS ENGINEERING
Report Date:
1986-05-01
Pagination or Media Count:
172.0
Abstract:
Directionally solidified Ds MAR-M246Hf was tested in tension and fatigue, at temperatures from 20 C - 1093 C. Tests were performed on 001 oriented specimens at strain rates of 50 and 0.5 per minutes. In tension, the yield strength was constant up to 704 C, above which the strength dropped off rapidly. A strong dependence of strength on strain rate was seen at the higher temperatures. The deformation mode was observed to change from heterogeneous to homogeneous with increasing temperature. Low Cycle Fatigue tests were done using a fully reversed waveform and total strain control. for a given plastic strain range, lives increased with increasing temperature. For a given temperature strain rate had a strong effect on life. At 704 C, decreasing strain rates decreased life, while at the higher temperatures, decreasing strain rates increased life, for a given plastic strain range. These results could be explained through considerations of the deformation modes and stress levels. At the higher temperatures, marked coarsening caused beneficial stress reductions, but oxidation limited the life. The longitudinal grain boundaries were found to influence slip behavior. The degree of secondary slip adjacent to the boundaries was found to be related to the degree of misorientation between the grains.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
