Abstract: Methods and apparatus are provided for forming a diffusion bonded composite structure. The composite structure includes at least one internal void or feature. Surfaces to be bonded are cleaned and prepared for bonding. The exposed joints of the composite structure where the surfaces interface are sealed. The composite structure is placed in hot isostatic process furnace. The furnace is pressurized to a low pressure below 1500 pounds per square inch that forces the surfaces to be bonded in intimate contact with one another. The composite structure is heated to promote diffusion bonding at the interface of surfaces in contact with one another.

Abstract: Apparatus for diffusion bonding, brazing, or joining between respective surfaces of two parts, e.g., the exterior wall of a first annular cylinder and the interior wall of a concentric second annular cylinder, includes a cylindrical body having a circumferential cavity positioned between upper and lower ends thereof. A flexible annular membrane is disposed concentrically over the cavity, and respective upper and lower ends of the membrane are each sealingly hinged to the body. The body is assembled coaxially within the first cylinder, and the assembly then inserted coaxially into the second cylinder to the desired axial bonding position. The cavity is pressurized, causing the membrane, and responsively, the first cylinder, to expand radially within the second cylinder. The temperature of the parts is then raised and maintained for a selected period of time to bond the respective walls of the two cylinders to each other.

Abstract: Methods and apparatus are provided for forming a diffusion bonded composite structure. The composite structure includes at least one internal void or feature. Surfaces to be bonded are cleaned and prepared for bonding. The exposed joints of the composite structure where the surfaces interface are sealed. The composite structure is placed in hot isostatic process furnace. The furnace is pressurized to a low pressure below 1500 pounds per square inch that forces the surfaces to be bonded in intimate contact with one another. The composite structure is heated to promote diffusion bonding at the interface of surfaces in contact with one another.

Abstract: A precipitation hardening, high strength alloy, having a composition comprising in weight percent, 25.0% nickel, 15.0% chromium, 1.25% molybdenum, 0.25% vanadium, 2.65% titanium, 0.25% aluminum, 0.005% carbon, and the balance iron with incidental impurities.

Abstract: An anchoring means for an earth works tunneling device includes a unit having two planar back-stop members secured together in spaced relation from one another. Between the back-stop members is provided a means for mounting the tunneling device so that a force exerted on the device is transmitted to the stop members. Thus, as the device drives or pulls a pipe or pipe stem through the earth, the counterreactive force is transmitted to one of the stop members which pushes against the adjacent earth bank so as to anchor the tunneling device.