Boeing North American, Inc.

Rockwell International Corporation

Sami M El-Soudani

In one broad aspect the present invention comprises the steps of providing a titanium-based material preform and superplastically forming the preform to a final helmet shape. In another broad aspect, a first piece of fiber-reinforced titanium matrix composite material is hot isostatically pressed (HIP'ed) to form a side wall section. A second piece of fiber-reinforced titanium matrix composite material is hot pressed to form an upper dome section. The side wall section is then HIP/diffusion bonded to the upper dome section.

Ballistic-resistant helmet and method for producing the same

The invention is a process for simultaneously improving at least two mechanical properties of mill-processed (.alpha.+.beta.) titanium alloy, which may or may not contain silicon, which includes steps of heat treating the mill-processed titanium alloy such that the (.alpha.+.beta.) microstructure of said alloy is transformed into an (.alpha.+.alpha..sub.2 +.beta.) microstructure, preferably containing no silicides. The heat treating steps involve subjecting the mill-processed titanium alloy to a sequence of thermomechanical process steps, and the mechanical properties which are simultaneously improved include (a) tensile strength at room, cryogenic, and elevated temperatures; (b) fracture toughness; (c) creep resistance; (d) elastic stiffness; (e) thermal stability; (f) hydrogen embrittlement resistance; (g) fatigue; and (h) cryogenic temperature embrittlement resistance. As a consequence of the process, the (.alpha.+.alpha..sub.2 +.beta.) microstructure contains equiaxed alpha phase strengthened with .alpha..sub.2 precipitates coexisting with lamellar alpha-beta phase, where the .alpha..sub.2 precipitates are confined totally to the equiaxed primary alpha phase. The invention also encompasses a composition of matter produced by the inventive process, especially one comprising a titanium alloy having an (.alpha.+.alpha..sub.2 +.beta.) microstructure.

Three phase .alpha.-.beta. titanium alloy microstructure

A process for enhancing the bond strength of resistance welded joints between titanium alloy articles includes a first step of resistance welding two titanium alloy articles and a second step of heat treating the resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675.degree. F. to 1825.degree. F. for a period of 15 minutes to 4 hours. The process of the present invention is particularly useful in providing efficient joining of face sheets to a honecomb core element.

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Cerritos, CA, United States of America

Sami M El-Soudani