Abstract: The present invention relates to a surface treatment apparatus and method for inducing compressive residual stress in the surface of a workpiece with dimensional variations. The method comprises the acts of measuring the dimensions of the workpiece during a surface treatment operation and adjusting the surface treatment process parameters to account for the measured dimensions. In one embodiment, the apparatus comprises two surface treatment elements oriented in opposition to one another in a caliper configuration. The surface treatment elements are positioned and impinged against the surface of a workpiece by an actuator controlled by a computer control unit. The depth to which the surface treatment elements are impinged is precisely controlled to achieve the desired magnitude and depth of compressive residual stress. A sensor operatively connected to the apparatus senses and relays the dimensions of the workpiece to a computer control unit that adjusts the operating parameters accordingly.

Abstract: A method and surface treatment apparatus for preventing or arresting the development and propagation of cracks in the material surrounding a fastener. The method includes introducing compressive residual stresses in the material surrounding the fastener. The compressive residual stresses offset the high residual tensile and applied stresses which the material may be subjected to in operation and thereby prevent or arrest the development of cracks. The surface treatment apparatus comprises a compression tool, positioning device and at least one sensor for determining the location of a fastener on the surface being treated. Using the output of the sensor, the surface treatment apparatus is positioned relative to a fastener. The compression tool is impinged against the surface of the material adjacent to the fastener and rotated around the perimeter of the fastener thereby inducing a zone of compressive residual stress.

Abstract: An article made of a metallic material and comprising a body and a body end portion integral with the body, includes a band of the metallic material at the end portion substantially through the entire end portion, the band being under a compressive stress greater than the body. An example of the article is a turbine engine blading member in which the body is the airfoil of the member and the band is disposed at the radially outer tip portion of the airfoil. One method for providing the band includes performing roller deformation on the end portion until a desired amount of compressive stress is developed in the band substantially through the entire end portion.

Abstract: A work holder capable of measuring the amount of distortion occurring in a part as the part is machined, processed, treated, or otherwise operated upon and methods of using the same for quality control and process monitoring purposes.

Abstract: The method and apparatus for performing the method of forming a weld joint of the present invention utilizes welding apparatus (100) having welded tool (102) and a compression tool (106) for inducing a layer of residual compressive stress along the surface of the weld line (18) and any heat affected regions with a controlled amount of cold working and surface hardening. In a preferred embodiment of the invention the compression tool (106) utilizes a single-point burnishing process to provide deep compression within the weld joint (20) with a minimal amount of cold working and surface hardening.

Abstract: This invention relates to a method and an apparatus for performing the method of inducing compressive residual stress along the surface of a part. In the preferred embodiment of the invention, the method includes burnishing or deep rolling a surface using a first and a second roller or ball burnishing members, whereby the first and second burnishing members may have a different diameter and/or modulus of elasticity. In another preferred embodiment of the invention, the burnishing operations may be performed while the surface of the part is at different temperatures.

Abstract: The shot peening method and apparatus (FIG. 13) of the present invention utilizes control of the shot peening coverage to provide higher surface compression and comparable depth of compression to conventional 100% coverage peening but with reduced cold working providing improved thermal stability and reduction in shot peening time and cost. A preferred embodiment of this invention employs x-ray diffraction (FIG. 13) residual stress and percent cold work determinated by line broadening to establish the optimal degree of coverage for a given material and shot peening intensity.