Influence of Grain Refinement on the Structure and Properties of Cast Nickel-Base Superalloy Turbine Components
Abstract
The influence of refinement of the cast grains on the mechanical properties of three nickel base superalloys (713LC, MAR-M-246 and C103) was determined. The investigation was conducted because improvements in the fatigue properties of integrally cast rotors for helicopters was desired. Grain refinement of all three alloys was accomplished by a controlled thermal cycling technique together with a boron addition to the melt. This refinement practice was successfully adapted to a production rotor casting. This grain refinement increased by a factor of 2 to 4 the number of cycles to failure in low cycle fatigue of 713LC and MAR-M-246. The fatigue behavior of C103 was insensitive to grain size. The yield strength of 713LC and MAR-M-246 was increased 10 ksi but the tensile strength and ductility slightly decreased by grain refinement. The 1800 F stress rupture properties of the refined alloys were slightly superior to the unrefined alloys at high stress levels and equal to or slightly inferior at low stress levels. At 1850 F and lower stress levels, the stress rupture properties of MAR-M-246 were somewhat reduced compared to the unrefined structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1977
- Accession Number
- ADA040246
Entities
People
- A. F. Denzine
- J. F. Wallace
- T. A. Kolakowski
- W. M. Matlock
Organizations
- Case Western Reserve University