Dwell-fatigue of a titanium alloy at room temperature under uniaxial or biaxial tension

Doquet, Véronique; Greef, Vincent de

doi:10.1016/j.ijfatigue.2011.12.007

Cited by 31 publications

(13 citation statements)

References 31 publications

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“…Under normal cyclic fatigue mode, cracks initiated in the surface region while interior crack initiation was found under dwell fatigue mode at V p of about 35%, see Figure 4. Similar observations were found in other investigations [2,[19][20][21][22][23][24][25][26][27] . At 10% of V p , cracks initiated at the subsurface region under normal cyclic loading while at the interior under dwell loading, see Figure 5.…”

Section: Fatigue Resultssupporting

confidence: 92%

Effect of Volume Fraction of Primary α Phase on Dwell and Normal Cyclic Fatigue Behavior of Ti60 Alloy

Liu¹,

Yang²,

Wang³

et al. 2016

Proceedings of the 13th World Conference on Titanium

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The dwell and normal cyclic fatigue behaviors of Ti-5.7Al-3.7Sn-3.5Zr-0.4Mo-0.4Si-0.4Nb-1.0Ta-0.05C (Ti60) forging with a bimodal microstructure at different volume fraction of primary phase (V p ) were investigated. Lower fatigue life was found under dwell fatigue condition than under normal cyclic condition regardless of the value of V p . However, dwell fatigue sensitivity tends to decrease with the decrease of V p . Interior crack initiation characterized by higher facet density was found for dwell fatigued specimens as compared to normal cyclic fatigued ones with fatigue cracks nucleating at the surface or subsurface. Fracture surface analysis based on 3D Measuring Laser Microscope indicates that cleavage occurred favorably at grains to form facets with their normal line at an angle not larger than 15° to the loading axis under dwell loading, while the angle is only less than 5° under normal cyclic loading. It was concluded that more grains involved in dwell fatigue damage which leads to lower fatigue life and higher dwell sensitivity with increase of V p and decrease of V p is helpful to alleviate this effect.

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Section: Fatigue Resultssupporting

confidence: 92%

Effect of Volume Fraction of Primary α Phase on Dwell and Normal Cyclic Fatigue Behavior of Ti60 Alloy

Liu¹,

Yang²,

Wang³

et al. 2016

Proceedings of the 13th World Conference on Titanium

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“…Biaxial tension can be applied to cruciform specimens loaded in two orthogonal directions, 1‐3 circular or elliptical plates submitted to biaxial bending 4‐6 and tubular specimens loaded in tension and internal pressure 7,8 . The effect of biaxial tension on fatigue lives was reported to be beneficial 9,10 or detrimental 11,12 or neutral 13 depending on the load biaxiality ratio. All these studies have however been conducted in ambient air, at room temperature, and very few studies on environmental effects on biaxial tension fatigue are available.…”

Section: Introductionmentioning

confidence: 99%

Corrosion‐fatigue behaviour of Cr–Mo steel under biaxial tension

Gaur

Doquet

Persent

et al. 2020

Fatigue Fract Eng Mat Struct

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Combined cyclic tension and internal pressure tests with various proportions of each loading were run on a 2.5%Cr-1%Mo steel in air and in 3.5% NaCl solution, with and without cathodic protection to investigate the effect of positive stress biaxiality on corrosion-fatigue lives and damage mechanisms. At free potential, a strong reduction in fatigue resistance was observed for uniaxial as well as for equibiaxial cyclic tension and attributed to multiple crack initiation from corrosion pits. Cathodic protection completely cancelled the detrimental effect of the corrosive environment on fatigue lives whatever the load biaxiality was, in spite of an obvious enhancement of intergranular fracture attributed to hydrogen embrittlement.

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“…This phenomenon known for about 40 years as "dwell-effect" can be observed on several titanium alloys, in particular on Ti6242. Different parameters seem to affect the dwell-effect and have been considered in earlier studies: microstructure [2], dwell time [3], temperature [4], hydrogen content [5,6], stress redistribution [7,8], sample size [9], "cold creep" (plastic strain accumulation under static load at room temperature) [10,11], biaxial and triaxial stress fields [12,13]. None of these studies has reached a complete understanding of the phenomenon and some of them are even contradictory.…”

Section: Introductionmentioning

confidence: 99%

Dwell Fatigue of a Fully Lamellar Ti6242 Alloy: Deformation Mechanisms at Different Scales

Thüngen

Delaleau

Villechaise

2016

Proceedings of the 13th World Conference on Titanium

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Ti6242 alloy is used for high pressure compressor disks in jet engines due to its good fatigue resistance at low and moderate temperatures. These parts undergo complex in-service thermomechanical loading that can be simulated on laboratory samples by introducing a dwell time at maximum stress in cyclic loading tests. The use of such trapezoidal signal appears more realistic than pure fatigue to simulate flights. Under these conditions, this alloy is well-known to present an important decrease of its lifetime when compared to standard fatigue. This phenomenon is commonly observed in metallic materials for high temperatures when viscoplasticity mechanisms are active. The fact that this decrease of the fatigue life resistance appears at room temperature for the Ti6242 has led the scientific community to name it "cold dwell effect". The present work aims at studying the microstructure configurations favoring micro-plasticity mechanisms during dwell cycling. Instrumented micro-samples are tested in situ in a SEM under tensile, creep and dwell conditions. Microstructure and deformation are analyzed at the scale of lamellae and colonies taking into account the local crystalline orientation (EBSD) and the morphological orientation (image processing). The appearance of micro-relief at large scale is also considered and quantified using white light interferometry. Relationships between microstructure, micro-texture and mechanical deformation are established.

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Dwell-fatigue of a titanium alloy at room temperature under uniaxial or biaxial tension

Cited by 31 publications

References 31 publications

Effect of Volume Fraction of Primary α Phase on Dwell and Normal Cyclic Fatigue Behavior of Ti60 Alloy

Effect of Volume Fraction of Primary α Phase on Dwell and Normal Cyclic Fatigue Behavior of Ti60 Alloy

Corrosion‐fatigue behaviour of Cr–Mo steel under biaxial tension

Dwell Fatigue of a Fully Lamellar Ti6242 Alloy: Deformation Mechanisms at Different Scales

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