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A Specially Constructed Metallograph for Use at Elevated TemperaturesA Metallographic microscope was developed with provision for heating a specimen to 1800 F in protective atmospheres, that is, vacuum or gas. A special objective was constructed of reflecting elements with an unusually long working distance (7/16 in.) and a high numerical aperture (0.5). Changes in specimen microstructure were observed and recorded on 35-millimeter motion-picture film. The resulting pictures were projected as motion pictures and individual frames were cut and enlargements made for close observation. Structural changes upon heating a 0.35-percent annealed carbon steel and a 5-percent tin phosphor bronze specimen were observed and recorded. Newly formed microstructure were revealed by selective vacuum etching and specimen relief resulting from recrystallization and varying grain orientation.
Document ID
19930086828
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Jenkins, Joe E
Buchele, Donald R
Long, Roger A
Date Acquired
August 16, 2013
Publication Date
September 11, 1951
Report/Patent Number
NACA-RM-E51G12
Accession Number
93R16118
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
INSTRUMENTS, LABORATORY
PHOTOMICROGRAPHIC APPARATUS - NACA
INSPECTION - METALS, HIGH-TEMPERATURE MICROSCOPIC
MATERIALS, PROPERTIES

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