Increasing the fatigue resistance of high-strength steel using bulk and surface treatments

Belozerov, Valery; Makhatilova, A. I.; Turovskii, M. L.; Shifrin, I. M.

doi:10.1007/bf00795278

Cited by 1 publication

(1 citation statement)

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“…Improvements in HCF, corrosion-fatigue, and stress corrosion cracking are documented, with f atigue strength enhancement attributed to improved finish, the development of a compressive surface layer, and the increased yield strength of the cold worked surface. [8][9][10][11][12][13] Optimum forces and rolling parameters were established to minimize roughness and/or maximize surface hardening. [14][15][16][17] Analytical models to predict the residual stresses have been attempted in England [18] and France.…”

Section: Nomenclature Lpb -mentioning

confidence: 99%

Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

Prevéy

Ravindranath

Shepard

et al. 2006

Journal of Engineering for Gas Turbines and Power

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Surface enhancement technologies such as shot peening, laser shock peening, and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The x-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including the following. (1) The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing the fatigue benefit of thermal stability at engine temperatures. (2) An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. (3) Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. (4) Corrosion fatigue mitigation with LPB in Carpenter 450 steel. (5) Damage tolerance improvement in 17-4 PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

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