Quantitative fractography and modelling of fatigue crack propagation in high strength AerMet®100 steel repaired with a laser cladding process

Walker, K, Lourenço, J, Sun, S, Brandt, M and Wang, C 2017, 'Quantitative fractography and modelling of fatigue crack propagation in high strength AerMet®100 steel repaired with a laser cladding process', International Journal of Fatigue, vol. 94, pp. 288-301.


Document type: Journal Article
Collection: Journal Articles

Title Quantitative fractography and modelling of fatigue crack propagation in high strength AerMet®100 steel repaired with a laser cladding process
Author(s) Walker, K
Lourenço, J
Sun, S
Brandt, M
Wang, C
Year 2017
Journal name International Journal of Fatigue
Volume number 94
Start page 288
End page 301
Total pages 14
Publisher Elsevier
Abstract Ultra-high strength steels employed in safety-critical applications, such as AerMet®100 used in aircraft landing gear structures, are managed on very conservative rejection criteria for small defects and repair options are limited. A novel repair technique using laser cladding has recently been developed. In the present paper we report a study of the fatigue endurance of AerMet®100 steel components repaired by the laser cladding process, and a fracture mechanics based model to predict the fatigue endurance of repaired components. Three different types of samples were tested; baseline AerMet®100 sample with a small electro-discharge machining notch to initiate a crack, as-clad repaired, and as-clad repaired followed by heat treatment to relieve residual stresses. The specimens were subjected to cyclic loading under a special sequence consisting of constant amplitude segments at two different stress-ratios (ratio of minimum to maximum cyclic stress). The test results showed that the crack propagation lives from a common initial depth of 0.25 mm for the as-clad samples were significantly longer than the baseline samples by a factor of three to four. The longer life is attributed to the beneficial compressive residual stresses resulting from the repair process. The model predictions are found to correlate well with the results of quantitative fractography measurements from samples tested under variable amplitude cyclic loads.
Subject Manufacturing Processes and Technologies (excl. Textiles)
Keyword(s) Crack closure
Crack growth
Laser cladding repair
Quantitative Fractography
Spectrum loading
Stress-intensity factor
Ultra-high strength steel
Variable-amplitude loading
DOI - identifier 10.1016/j.ijfatigue.2016.06.031
Copyright notice Crown Copyright © 2016 Published by Elsevier Ltd. All rights reserved.
ISSN 0142-1123
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