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

Report Date:

1964-12-01

Pagination or Media Count:

55.0

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.

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE