Torsion fatigue behavior of pure titanium with a gradient nanostructured surface layer

Wang, Qi; Sun, Qiaoyan; Lin, Xin; Sun, Jun

doi:10.1016/j.msea.2015.09.104

Cited by 21 publications

(19 citation statements)

References 37 publications

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“…This indicates that fatigue damage mechanism of cold-drawn copper is shear. This result is similar to those observed in torsional fatigue of pure titanium [7] and aluminum alloys [6,8]. At the stress amplitude of 75 MPa, the largest part of the main crack is along the transverse direction, except that a very small portion is along the longitudinal direction, which leads to the appearance of small steps (Fig.…”

Section: Surface Morphologysupporting

confidence: 88%

“…Therefore, shear stress can cause fatigue damage and is recognized as the driving force for fatigue crack initiation under cyclic loading [5]. After crack initiation on the maximum shear stress plane, the propagation of torsional fatigue crack can be divided into the following three types: (1) cracks extend on maximum shear planes [6][7][8]; (2) the cracks grow firstly on planes of maximum shear, then transfer to the planes with maximum normal stress [9][10][11][12]; (3) the cracks propagate on maximum normal stress planes [13]. Because torsional fatigue cracks often have a long stage I propagation [5,14,15], the crack propagation mode of most metal shaft components belongs to the first two types, and the initial propagation of a fatigue crack usually occurs along the maximum shear stress plane, i.e., the transverse or longitudinal section.…”

Section: Introductionmentioning

confidence: 99%

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Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress

Zhang

2019

Acta Metall. Sin. (Engl. Lett.)

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The fatigue cracking and fracture behavior of cold-drawn copper subjected to cyclic torsional loading were investigated in this study. It was found that with increasing stress amplitude, the fracture mode of cold-drawn copper gradually changes from a shear fracture on transverse maximum shear stress plane to a mixed shear mode on both transverse and longitudinal shear planes and finally turns to the shear fracture on multiple longitudinal shear planes. Combining the cracking morphology and the relationship between torsional fatigue cracking and the grain boundaries, the fracture mechanism of cold-drawn copper under cyclic torsional loading was analyzed and proposed by considering the effects of the microstructure and axial stress caused by torsion. Because of the promotion of the grain boundary distribution on longitudinal crack propagation and the inhibition of axial stress on transverse crack grown, the tendency of crack propagation along the longitudinal direction increases with increasing stress levels.

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Section: Surface Morphologysupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress

Zhang

2019

Acta Metall. Sin. (Engl. Lett.)

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“…The residual compressive stress is beneficial to the fatigued life of aviation components. 19,20 Surface grain layer can be gradually refined to 3–7 nm. 21 Then the nanocrystalline layer is formed under the action of USRP.…”

Section: Resultsmentioning

confidence: 99%

“…This process can reduce the friction coefficient, enhance the wear resistance, and extend the service life. 23–25 If some microprotrusions are produced on the surface of ultrasonic rolling tool, many surface textures may form on the surface of spherical plain bearing during the USRP process. These surface textures can provide good lubrication to spherical plain bearing.…”

Section: Resultsmentioning

confidence: 99%

Synergistic effects of surface strengthening and surface micro-texture on aviation spherical plain bearing tribological properties

Yuan

Qin

Денг

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part J:

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With an increase in extreme and complex work conditions in the fields of aircraft industry and high-speed train, single surface strengthening or single surface machining is not satisfactory with repeated requests of spherical plain bearings, which results in serious wear. Therefore, in this paper, a compound method of ultrasonic surface rolling process and surface texture was proposed on the basis of investigating the wear mechanism to meet the tribological property requirements of spherical plain bearings. The theoretical and experimental results show that low micro-hardness and low shear strength of surface material, rough surface, and poor lubrication are the important factors contributing to the wear of spherical plain bearings. The surface roughness Ra and Rz of processed spherical plain bearings are reduced to 0.02 mm and 0.14 mm from 0.35 mm and 2.1 mm, respectively, and the micro-hardness of surface material is increased by about 20%. The double-sine micro-textures with the width of 120 mm and the depth of 20 mm produced by laser machine, together with the circular groove, provide satisfactory lubrication for the spherical plain bearings. Finally, the wear resistance properties of spherical plain bearings were increased by more than 55%. The proposed synergistic methods have great advantages in improving the tribological properties of key fundamental components, especially for spherical plain bearings.

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“…Besides superior combination of strength and ductility in uni-axial tensile tests, the gradient-structured metals also exhibit significant improvement in fatigue strength when subjected to cyclic loads [9][10][11][12]. The researchers conclude that the improved fatigue strength is due to the synergistic effects of compressive residual stress and the gradient nanograined-structured surface layer, which suppresses the initiation of a fatigue crack.…”

Section: Introductionmentioning

confidence: 96%

Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

et al. 2021

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The gradient nanostructured (GNS) layer forms beneath the surface of Zr-4 samples by the surface mechanical grinding treatment (SMGT) process, which increases the fatigue strength apparently due to the synergistic effect of the gradient nanostructured layer and compressive residual stress. The SMGTed Zr-4 samples are subjected to annealing to remove residual stress (A-SMGT) and the individual effect of the GNS layer and compressive residual stress can be clarified. The results show that the gradient nanostructure in the surface is stable after annealing at 400 °C for 2 h but residual stress is apparently removed. Both SMGTed and A-SMGTed Zr-4 samples exhibit higher fatigue strength than that of coarse-grained (CG) Zr-4 alloy. The fatigue fracture of Zr-4 alloy indicates that the hard GNS surface layer hinders fatigue cracks from approaching the surface and leads to a lower fatigue striation space than that of CG Zr-4 samples. The offset fatigue strength of 106 cycles is taken for SMRT-ed, A-SMRT-ed, and CG Zr-4 samples and the results indicate clearly that the GNS surface layer is a key factor for the improvement of fatigue strength of the Zr-4 alloy with surface mechanical grinding treatment.

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Torsion fatigue behavior of pure titanium with a gradient nanostructured surface layer

Cited by 21 publications

References 37 publications

Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress

Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress

Synergistic effects of surface strengthening and surface micro-texture on aviation spherical plain bearing tribological properties

Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

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