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National Advisory Committee for Aeronautics, Technical Notes - Office of Naval Research and NACA Metallurgical Investigation of a Large Forged Disc of S-816 Alloy

This report is one of a series in a cooperative research investi—
gation undertaken to ascertain the properties of the better wrought
heat—resisting alloys in the form.of.large discs required for gas—
turbine rotors.

The properties of large discs of 8—816 alloy have been determined
for both the as—forged and aged condition (disc NR—76BAF) and the
heat—treated and aged condition (disc NR—76B—Q) at room.temperature
and, by means of stress—rupture and creep tests for time periods up to
about 2000 hours, at 12000, 13500, and 15000 F. Short—time tensile test,
impact test, and time—deformation characteristics are included.

This report presents the results of a study of the roonbtemperature,
12000, 13500, and 15000 F properties of a large forged disc of 3-816 alloy.
One—half of the disc was tested as—forged and aged, and the other half
was heat—treated and aged before testing. The halves are referred to
herein as two discs, NR—76B—F (forged and aged) and NR—76B—Q (heat—
treated and aged).

The primary purpose of this study was to determine the level of
properties exhibited by this alloy in the form of large forgings of
the type required for rotor wheels of gas turbines and to determine
the relative properties of such forgings as—forged and aged and as
heat—treated and aged. The results obtained previously from similar
investigations of l9—9DL, GSA, Timken alloy, EME, and lOtharbon
N—l55 discs have been published as references 1 to 9. A concurrent and
nearly identical investigation of a large forged disc of 8—590 alloy has
been published as reference 10.

This work is being carried out as part of two correlated programs
of research on alloys for gas—turbine applications in progress in
this country. The National Advisory Committee for Aeronautics is
sponsoring work directed toward the development of improved high—
temperature alloys for gas turbines used in aircraft power plants.

A concurrent program, formerly sponsored by the National Defense Research
Comittee, Office of Scientific Research and Development, and now
sponsored by the Office of Naval Research, Navy Department, is being
directed to the deve10pment of alloys for gas—turbine applications in
general and, in particular, for both ship and aircraft propulsion
turbines. The work described herein was accomplished with the financial
assistance of the National Advisory Committee for Aeronautics and the
Office of Naval Research, Navy Department.