H. R. Ogden

Heat treatment, structure, and mechanical properties of Ti-Mn alloys

Ti-Mn alloys were studied in order to determine the factors affecting the mechanical properties of β-stabilized titanium alloys. The principal compositional factors have been found to be solid-solution strengthening, the martensitic transformation, and instability of the β phase. Structural factors, such as grain size and shape, were found to have more influence on ductility and toughness than on strength.

Structure and Properties of Ti-C Alloys

The mechanical properties of Ti-C and Ti-C-O alloys can be altered by heat treatments to dissolve or reject carbon from solid solutions. The maximum strength is obtained by annealing just below the peritectoid temperature. Quenching from the β-carbide field results in softening. Impact behavior is influenced by the extent of solution of interstitials.

MECHANICAL PROPERTIES OF ALPHA TITANIUM AS AFFECTED BY STRUCTURE AND COMPOSITION

The effects of grain size and shape on alloys of titanium with nitrogen and aluminum have been determined. Increasing α grain size decreases strength and hardness and increases impact resistance. Quenching from the β field produces subgrain markings delineating α plates in Ti-N alloys but not in Ti-Al alloys. This suggests a precipitation from the high nitrogen alloys.

CONSTITUTION OF TITANIUM-ALUMINUM ALLOYS

Aluminum has been found to be soluble in α titanium to about 26 pct, and to raise the temperature range of transformation from α to β. Two intermediate phases exist in the system, a new face-centered tetragonal phase, designated as γ, which occurs between 34 and 46 pct Al, and TiAl3. Metallographic and X-ray diffraction data were used to determine the diagram.

Effect of Alpha Sohites on the Heat-Treatment Response Of Ti-Mn Alloys

Alpha solutes increase the strengths of Ti-Mn alloys through solid-solution strengthening. The substitutional α addition, aluminum, decreases, and the interstitial solutes, carbon and nitrogen, increase the rate of nucleation and growth of a from β. The best combinations of properties of α-β alloys are obtained when there is α sufficient quantity of a phase in the structure to dissolve the α solutes.

The U. S. Navy Titanium Program

Preliminary research to develop suitable alloys and the direction of future work is discussed.

Formation and Initial Growth of Single‐Asperity Solid‐State Bonds

A gold needle point in contact with a gold flat has been used to study the formation and initial growth of single‐asperity solid‐state bonds. In the absence of external pressure, the growth of the bonded area can be expressed analytically by a diffusion‐controlled rate equation. Values for the coefficient of self‐diffusion determined from these experiments are in reasonable agreement with those given in the recent literature.

TANTALUM ALLOY SHEET IN PILOT PRODUCTION

The fabrication of two tantalum alloys—Ta-10Hf-5W and Ta-30Cb-7.5V—into sheet bar by extrusion, forging, and rolling is investigated and evaluated. The properties of the resulting sheet—especially its tensile properties and bend and weld ductility—are reported. Indications that sound fusion welds in the Ta-Cb-V alloy cause no appreciable loss in strength or ductility are given.

A statistical analysis applied to arc melting tungsten-base alloys

From the above relation, it is apparent that input power is directly related to melting rate, electrode density, and a weighted sum of the ingot and electrode cross-sectional areas. Also, since the data used in the analysis were obtained from seven different melting facilities, it can be concluded that existing differences between melting practices and furnace designs have little or no effect on the correlation among the variables of several sources. A higher degree of correlation, however, might have resulted if sufficient data had been available from a single source and a single alloy composition.

Tantalum Alloys for Elevated-Temperature Service

Early results of a tantalum alloy development program have shown that high hot-strength properties can be attained while maintaining low-tem- perature toughness and ductility.