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Title: Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium

Abstract

Fretting fatigue damage occurs at the contact between two surfaces, when a static load perpendicular to the interface and a cyclic load parallel to the surfaces are present. The fretting fatigue damage occurring on the surface is known to be responsible for initiation of surface breaking cracks and dramatic reduction of fatigue life of the materials and components. Many premature failures of the engine components of advanced fighter aircrafts have been attributed to the fretting fatigue damage. Though fretting fatigue damage occurs at the surface, NDE techniques have limited success in detecting early stages of damage. This paper presents a methodology based on optical profiling of the surface to evaluate the progression of damage in fretting fatigue damaged specimens of shot peened Ti-6Al-4V. Surface topography measurements performed using a white light interference microscope were analyzed to identify the surface texture parameters sensitive to progressive damage. Results of the relation between the number of fretting fatigue cycles, surface texture parameters, residual stress and the changing microstructure are presented. Potential of the optical surface profiling as a nondestructive evaluation tool for characterization of the fretting fatigue damage is discussed.

Authors:
;  [1];  [2];  [3]
  1. Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433 (United States)
  2. University of Dayton Research Institute, 300 College Park, Dayton, OH 45467-0127 (United States)
  3. Air Force Institute of Technology, Wright Patterson Air Force Base, OH 45433 (United States)
Publication Date:
OSTI Identifier:
20798228
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 820; Journal Issue: 1; Conference: Conference on review of progress in quantitative nondestructive evaluation, Brunswick, ME (United States), 31 Jul - 5 Aug 2005; Other Information: DOI: 10.1063/1.2184684; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRACKS; DAMAGE; FAILURES; FATIGUE; INTERFACES; MICROSTRUCTURE; NONDESTRUCTIVE ANALYSIS; NONDESTRUCTIVE TESTING; OPTICAL MICROSCOPY; RESIDUAL STRESSES; SURFACES; TEXTURE; TITANIUM; TITANIUM ALLOYS; WEAR

Citation Formats

Martinez, S. A., Blodgett, M. P., Sathish, S., and Mall, S. Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium. United States: N. p., 2006. Web. doi:10.1063/1.2184684.
Martinez, S. A., Blodgett, M. P., Sathish, S., & Mall, S. Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium. United States. doi:10.1063/1.2184684.
Martinez, S. A., Blodgett, M. P., Sathish, S., and Mall, S. Mon . "Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium". United States. doi:10.1063/1.2184684.
@article{osti_20798228,
title = {Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium},
author = {Martinez, S. A. and Blodgett, M. P. and Sathish, S. and Mall, S.},
abstractNote = {Fretting fatigue damage occurs at the contact between two surfaces, when a static load perpendicular to the interface and a cyclic load parallel to the surfaces are present. The fretting fatigue damage occurring on the surface is known to be responsible for initiation of surface breaking cracks and dramatic reduction of fatigue life of the materials and components. Many premature failures of the engine components of advanced fighter aircrafts have been attributed to the fretting fatigue damage. Though fretting fatigue damage occurs at the surface, NDE techniques have limited success in detecting early stages of damage. This paper presents a methodology based on optical profiling of the surface to evaluate the progression of damage in fretting fatigue damaged specimens of shot peened Ti-6Al-4V. Surface topography measurements performed using a white light interference microscope were analyzed to identify the surface texture parameters sensitive to progressive damage. Results of the relation between the number of fretting fatigue cycles, surface texture parameters, residual stress and the changing microstructure are presented. Potential of the optical surface profiling as a nondestructive evaluation tool for characterization of the fretting fatigue damage is discussed.},
doi = {10.1063/1.2184684},
journal = {AIP Conference Proceedings},
number = 1,
volume = 820,
place = {United States},
year = {Mon Mar 06 00:00:00 EST 2006},
month = {Mon Mar 06 00:00:00 EST 2006}
}
  • An experimental formula has been proposed to estimate the bending fatigue strength of carburized gears from the hardness and the residual stress. The derivation of the formula is briefly reviewed, and the effectiveness of the formula is demonstrated in this article. The comparison with many test results for carburized and shot-peened gears verifies that the formula is effective for the approximate estimation of the fatigue strength. The formula quantitatively shows a way of enhancing fatigue strength, i.e., the increase of hardness and residual stress at the fillet. The strength is enhanced about 300 MPa by an appropriate shot peening, andmore » it can be improved still more by the surface removal by electropolishing. 25 refs.« less
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  • Because of their frequency-dependent penetration depth, eddy current measurements are capable of mapping the near-surface depth profile of the electrical conductivity. This technique can be used to nondestructively characterize the subsurface residual stress distribution in certain types of shot-peened metals, e.g., in nickel-base superalloys. For quantitative evaluation of the experimental results, analytical and computational techniques are needed to solve the direct and inverse problems, i.e., to predict the frequency-dependent apparent eddy current conductivity from the depth profile of the frequency-independent intrinsic electrical conductivity of the specimen and vice versa. Simple analytical approximations are presented for both the direct and inversemore » eddy current problems by exploiting two specific features of the electrical conductivity variation caused by near-surface residual stresses in shot-peened metals. First, compressive residual stresses are limited to a shallow surface region of depth much less than typical probe coil diameters. Second, the change in electrical conductivity due to residual stresses is always very small, typically less than 1%. The proposed approximations are verified by numerical comparison to much more complicated numerical solutions.« less
  • The present study deals with the recovery of work-hardened layers, which are often encountered in mechanical parts. Two simple cases are studied for the 38Cr4Mo steel: the shot-peened layer of semi-infinite bodies and a ground surface. The latter case is applied to in situ tensile samples using the gold microgrids technique developed at PMTM Laboratory in order to determine some possible dimensional changes. Both work-hardened layers show the existence of macroscopic straining during the recovery. For the only shot-peened layer, a phenomenological study provides the evolution of the residual stresses and the integral breadth depth profiles using X-ray diffractometry. Amore » method is proposed to determine the recovery strain field from the residual stresses evolution. As the only possible strain on a semi-infinite body lies along the normal axis to the surface, calculated recovery strains are compared with the dimensional measurements. On the microstructural viewpoint, the modified Warren-Averbach's analysis is quickly presented and is performed to analyze the X-ray peak broadening through the affected layer of a shot-peened sample. Several corrections and deconvolution calculations of the X-ray profiles finally lead to the second and third types of broadening effects and their microstructural interpretations.« less