DEVELOPMENT OF SUPERIOR STEELS FOR PRECISION GYRO SPIN BEARINGS.
Abstract
Techniques are developed for casting thin section, rapidly chilled plates and bearing races of ferrous alloys. Reduced pressure is used to draw molten metal into a copper (or composite copper-refractory) mold. Primary dendrite arm spacings (and hence segregate spacings) obtained in these castings are extremely fine, ranging from 4 microns at the surface of a 0.10 cm. thick cast plate to 46 microns at the center of a 0.64 cm. thick plate. For comparison, segregate spacing in commercial bar stock from a consumable electrode ingot reduced by working as much as 115 to 1 was 45 microns. Segregate spacing is important since homogenization time necessary to reach a given low 'residual segregation index' varies inversely as the square of this spacing. A series of inner and outer bearing races were cast using procedures developed and heat treated to a residual segregation index less than 0.10. A series of inner and outer bearing races were also cast of 440C; discussion is included of effects of rapid solidification, and of homogenization, on structure of this material.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1964
- Accession Number
- AD0611538
Entities
People
- D. R. Poirier
- Merton C. Flemings
- R. F. Polich
Organizations
- Massachusetts Institute of Technology