Dovetail Peening By The Deflector Method

Author:  Happ, M. B.
Source:  Conf Proc: ICSP-3, (p.117-124)
Doc ID:  1987016
Year of Publication:  1987
Abstract:  
Shot peening is finding increased acceptance as a way to provide extra assurance against fatigue crack initiation and to extend the life of rotating turbomachinery. Often the life limiting area on a turbine or compressor disk is a hole or dovetail slot, which must be peened properly to obtain maximum benefit. A method for peening the interior surfaces of a hole has been described previously. The established practice of peening with external nozzles relies on uncontrolled ricocheted shot to cover areas of high service stress, such as dovetail pressure faces, which are not directly in the shot stream. This practice is sensitive to peening conditions, especially when the length of the dovetail slot is considerably greater than its width. Controlled deflector peening has been used effectively for holes in engine components where there is a large thickness-to-diameter ratio. More recently this technique has been applied to single and double tang dovetails in compressor and turbine disks to assure that residual compressive stresses of substantial magnitude and depth are developed in a uniform layer over the entire dovetail surface area. This is particularly important for the pressure faces where the crush stress produced by the outward radial load imposed by the mating blade dovetail is greatest.