Accession Number : AD0611538

Title :   DEVELOPMENT OF SUPERIOR STEELS FOR PRECISION GYRO SPIN BEARINGS.

Descriptive Note : Final rept. for 3 Sep-31 Dec 63,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY AND MATERIALS SCIENCE

Personal Author(s) : Poirier,D. R. ; Polich,R. F. ; Flemings,M. C.

Report Date : DEC 1964

Pagination or Media Count : 55

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.

Descriptors :   (*STEEL, BEARINGS), (*BEARINGS, GYROSCOPES), (*GYROSCOPES, BEARINGS), (*METALLURGY, STEEL), CASTING, CASTING ALLOYS, CARBON, CHROMIUM, MANGANESE, SILICON

Distribution Statement : APPROVED FOR PUBLIC RELEASE