J. W. Freeman

Raymond Frank Decker

John Paul Rowe

The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

Vacuum-induction, Vacuum-arc, and Air-induction Melting of a Complex Heat-resistant Alloy

Henry J. Gomberg

George C. Towe

Autoradiography has been used only to a rather limited extent in metallurgical studies. Probably the major deterring factor has been that the autoradiographic systems have not provided the high resolution required in many investigations. A general discussion of the requirements for high-resolution autoradiography is presented in this report including detecting layer as well as radioactive-sample specifications. The need for a thin photographic emulsion in close contact with the metal surface is emphasized. The desirability of using favorable radiation (e.g., low-energy beta radioactivity) is also discussed.

High-resolution Autoradiography

United States. National Advisory Committee for Aeronautics

Stuart C. Brown

Howard J. Curfman

Benjamin Milwitzky

George E. Solomon

George E. Towe

Morris Morduchow

P. S. Klebanoff

Stanley Corrsin

William C. Triplett

Alan L. Kistler

Dean C. Lindquist

Dexter M. Potter

G. Allan Smith

Theoretical and Analog Studies of the Effects of Nonlinear Stability Derivatives on the Longitudinal Motions of an Aircraft in Response to Step Control Deflections and to the Influence of Proportional Automatic Control

J. W. Freeman

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