Characterization of Fatigue Behavior of Bonded Composite Repairs

Abstract The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

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Characterization of Fretting Fatigue Behavior of TiN/Ti Coating on Ti-811 Alloy at Increased Temperature

Lecture Notes in Electrical Engineering - Proceedings of the First Symposium on Aviation Maintenance and Management-Volume II ◽

10.1007/978-3-642-54233-6_77 ◽

2014 ◽

pp. 699-705

Author(s):

Xiaohua Zhang ◽

Feng Pan ◽

Dinggen Xiang

Keyword(s):

Fatigue Behavior ◽

Fretting Fatigue ◽

Increased Temperature

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Basic Characterization of the Fatigue Behavior of Welded Joints

Fatigue Life Analyses of Welded Structures ◽

10.1002/9780470612149.ch2 ◽

2010 ◽

pp. 11-35

Keyword(s):

Welded Joints ◽

Fatigue Behavior

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Influence of Cyclic Deformation Induced Phase Transformation on the Fatigue Behavior of the Austenitic Steel X6CrNiNb1810

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.1231 ◽

2014 ◽

Vol 891-892 ◽

pp. 1231-1236 ◽

Cited By ~ 5

Author(s):

Andreas Sorich ◽

Marek Smaga ◽

Dietmar Eifler

Keyword(s):

Phase Transformation ◽

Fatigue Life ◽

Austenitic Steel ◽

Cyclic Deformation ◽

Deformation Behavior ◽

Fatigue Behavior ◽

Cyclic Hardening ◽

Martensite Formation ◽

Destructive Testing

The austenitic steel X6CrNiNb1810 (AISI 347) was investigated in isothermal total strain-controlled tests at ambient temperature and T = 300 °C in the LCF-and HCF-range. The phase transformation from paramagnetic austenite (fcc) into ferromagnetic α´-martensite ́(bcc) leads to cyclic hardening and to an increase in fatigue life. At 300 °C no α´-martensite formation was observed in the LCF-range and the cyclic deformation behavior depends basically on cyclic hardening processes due to an increase of the dislocation density, followed by cyclic saturation and softening due to changes in the dislocation structure. In the HCF-range an increase in fatigue life was observed due to ε- and α´-martensite formation. Measurements of the mechanical stress-strain-hysteresis as well as temperature and magnetic properties enable a characterization of the cyclic deformation behavior and phase transformation in detail. The changes in the physical data were interpreted via microstructural changes observed by scanning-and transmission-electron-microscopy as well as by x-ray investigations. Additionally electromagnetic acoustic transducers (EMATs) developed from the Fraunhofer Institute of Non-destructive Testing (IZFP) Saarbrücken were used for an in-situ characterization of the fatigue processes.

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