Abstract: By coating a workpiece with a uniform layer of polyimide containing surfactant upon the nonweld areas, spatter produced in electron beam welding of the workpiece is prevented from adhering to the workpiece surface in the nonweld areas. The polyimide coating is so constituted as to be adherent, heat stable, acid resistant, and chemically removeable. Silicone surfactant is preferred.

Abstract: Disclosed are coatings which are improved by a special peening process. Uniform sized spherical steel shot, in the range 1-2.5 mm is impacted at uniform low velocities onto a coated workpiece. Peening intensities are in the range 0.30-0.60 mm N. MCrAlY high temperature coatings are particularly improved, with densities of the order of 99 percent. Physical vapor desposited coatings have surface finishes of the order of 30.times.10.sup.-6 inch AA (Arithmetic Average) and plasma sprayed coatings have finishes of the order of 100.times.10.sup.-6 inch AA compared to unpeened finishes of 50-60.times.10.sup.-6 inch AA and 200-300.times.10.sup.-6 AA respectively.

Abstract: In shot peening apparatus, a device is provided for sensing shot peening intensity and the uniformity of shot flow. It is basically comprised of a detector plate mounted on a cantilevered arm; torque created at the arm mounting due to the impact of shot is measured with a transducer. The detector is mounted on a structure adapted to translate the detector through a large shot peening zone. The invention is especially suited for assuring consistency in a process wherein uniform spherical shot is gravity accelerated to impact a workpiece with uniform velocity.

Abstract: A method for simultaneously shot peening and smoothing includes use of relatively large, smooth, hard, spherical steel shot having a substantially uniform diameter in the range 1-2.5 mm. Titanium workpieces are provided in one step with a compressive stress layer of the order of 0.13 mm and a surface finish of better than 15.times.10.sup.-6 inch AA, compared to conventional peened finishes of the order of 40.times.10.sup.-6 inch AA. Surface finish and peening intensity are inter-related and dependent on shot diameter, mass, velocity, and energy within relatively small limits. The shot diameter is uniform within .+-.0.05 mm; the shot impact velocity is uniform within .+-.4 percent or less, in the range 1.4-12 m/s.

Abstract: In apparatus for shot peening, gravity is used to accelerate uniform sized steel shot, and thereby impart a combination of good surface finish and uniform compressive stresses to workpieces. It is especially useful for finishing gas turbine airfoils. Shot is introduced into the peening enclosure (28) through a gate (40) at near zero velocity. It is then accelerated along a streamline (31) toward the workpiece (18) with uniform velocity. The workpiece, positioned along the streamline, can be manipulated in three rotational modes: oscillatory rotation to uniformly peen contoured surfaces of a workpiece, periodic incremental rotation to peen different sides of a workpiece; and, tilting motion to enable peening of shoulders (22). The apparatus is especially suited to peening fragile workpieces such as gas turbine airfoils (18). A diverter plate (44) intercepts the shot stream at times when repositioning of a fragile workpiece is undertaken.

Abstract: Disclosed is a two step process of peening for workpieces having small radii fillets or fragile edges, such as gas turbine airfoils have. In the first step, relatively small size shot of less than 1 mm dia is used to impart a first peening intensity to a workpiece. This results in a first relatively rough surface finish. In the second step, shot of substantially uniform diameter in the range 1-2.5 mm is impacted with uniform velocity to provide a surface finish smoother than 30AA (10.sup.-6 inch). When fillets are peened, improved fatigue life results from the duplex process. When used on edges, where direct edge impact is avoided in the second step, deformed edges are avoided by the process. Yet the workpiece is substantially smooth and the edges have the requisite residual stress distribution.

Abstract: Shot peening of thin edges of workpieces which are subject to deformation damage by direct impacts is accomplished by rotating the workpiece edge near centerline through a particular angle measured from the normal to the shot streamline. The angle is sufficient to cause oblique blows on the centerline of the edge, but insufficient to cause direct impacts. Compressive stresses by the oblique blows provide residual compressive stresses along the centerline to the desired depth. The angle is calcuable from the edge radius, the depth of stressing desired at the centerline, and the depth of stressing produced by shot at a reference location. Oscillatory rotation is preferably used to obtain even peening.

Abstract: A metal electroform suitable for hot isostatic pressing (HIP) of metal powders and the fabrication process therefor is disclosed. Ordinary nickel electroplate is permeable to gases during HIP, e.g., at 1200.degree. C. and 100 MPa. An exemplary improved container is comprised of a first electroplated layer of nickel, a second layer of copper and a third layer of nickel, wherein the container has been heated to about 1150.degree. C. and then cooled, to cause fusing of the second lower melting point layer. During fusing there is limited alloying between the layers, the first and third layers retaining the desired container shape.

Abstract: Disclosed is apparatus and method for electrochemically finishing the edges of airfoils and other thin edged objects. When the edge on an airfoil varies in thickness along its length, a tapered electrode is provided which has both a decreased diameter and increased spacing distance, providing a means for obtaining an edge with a radius proportioned to the thickness. Generally, in the system having an electrode with a unit surface area A, and with an electrode-workpiece surface spacing distance S, both A and S are changed so that the ratio A/S is lowered for electrode portions proximate to edge portions having lowered thickness.

Abstract: An interlayer for transient liquid phase diffusion bonding is provided by depositing a metallic coating on at least one of the superalloy surfaces to be bonded and boriding a portion of the metallic coating to form a working coating having an overall composition resembling that of an interlayer alloy and an overall melting temperature less than that of the superalloys. When the superalloy surfaces are placed in contact and heated to above said melting temperature, the partially borided metallic coating functions as an interlayer alloy to effect bonding.

Abstract: An improved diffusion bonding fixture for holding workpiece surfaces in opposed contacting relation and exerting controlled pressure across the surfaces is disclosed. The fixture includes components having different thermal expansion characteristics which hold the workpiece surfaces together and generate pressure on the surfaces upon heating to the bonding temperature. The fixture also includes one or more pressure-controlling shim members disposed between the components of the fixture, the shim members being selectively and controllably deformed by the expanding components to control said bonding pressure at the desired value and to prevent unwanted distortion of the workpiece surfaces and fixture components. The fixture is especially useful in bonding workpiece surfaces of highly complex configurations, such as those associated with gas turbine blades, vanes and the like.

Abstract: Disclosed is apparatus and method for electrochemically finishing the edges of airfoils and other thin edged objects. When the edge on an airfoil varies in thickness along its length, a tapered electrode is provided which has both a decreased diameter and increased spacing distance, providing a means for obtaining an edge with a radius proportioned to the thickness. Generally, in the system having an electrode with a unit surface area A, and with an electrode-workpiece surface spacing distance S, both A and S are changed so that the ratio A/S is lowered for electrode portions proximate to edge portions having lowered thickness.