Improvement of low-cycle fatigue resistance in TWIP steel by regulating the grain size and distribution

Shao, Chenwei; Zhang, P.; Zhu, Yansong; Zhang, Z.J.; Pang, J.C.; Zhang, Z.F.

doi:10.1016/j.actamat.2017.05.004

Cited by 117 publications

(31 citation statements)

References 67 publications

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“…For instance, refs. [4][5][6][7] showed that pre-torsion enhances the tensile property and fatigue strength in LCF and HCF regime of steels, ref. 10 showed that pre-torsion increases the tensile strength of pure titanium, and ref.…”

Section: Methodsmentioning

confidence: 99%

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy

Pan

Qian

et al. 2020

Sci Rep

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Gradient structure (GS) is commonly designed and processed in engineering materials to improve mechanical properties especially fatigue performance by taking advantage of the strengthened surface. However, whether the very-high-cycle fatigue (VHCF) property can be improved by GS is questioning due to the different crack initiation mechanisms between low-, high-cycle and VHCF. In this paper, GS of a Ti-6Al-4V alloy is generated by pre-torsion and characterized by electron backscatter diffraction. Then the VHCF behavior of the GS specimen is studied. The fractography and synchrotron radiation X-ray microtomography presented detailed characteristics of the internal crack initiation region in VHCF of the titanium alloy with GS. The results indicated that, in contrast to the low-and high-cycle regimes, the VHCF strength is reduced for the specimens with GS. Thus, the GS induced by pre-torsion cannot enhance the VHCF strength of the titanium alloy. This implies that VHCF test (property) is an important consideration for the microstructural designed materials. The graphical abstract is available in Supplementary information.Fatigue damage causes the failure of more than 90% engineering materials and structures. According to the traditional knowledge, fatigue crack initiates from the surface of material 1 . Therefore, many surface strengthening methods, such as surface mechanical attrition or grinding treatment, surface quenching, shot peening, etc., have been widely used as counter strategies to improve the fatigue resistance of the components by introducing the refined microstructure with gradient distribution of grain size and residual compressive stress 2,3 . It is known that crack is hard to initiate from small grains, and the residual compressive stress may enhance the fatigue strength 1,2 . In recent years, pre-torsion method was used to produce gradient structure (GS) in metallic materials owing to its low cost and easy processing 4-7 . During the pre-torsion process, grain size can be substantially refined due to severe plastic deformation (SPD) 8 , and the GS is generated by the gradient strain. A number of experimental results 9,10 confirmed that the layer of GS improves fatigue property in low-cycle-fatigue (LCF) and high-cycle-fatigue (HCF) regimes, i.e. for the cases that the number of fatigue failure cycles is lower than 10 7 . However, with the development of modern civilization, there is practical demand of engineering structures for more than 10 7 loading cycles of safe performance. Thus, very-high-cycle fatigue (VHCF) has become an important topic, and has received increasing attention [11][12][13] . However, VHCF test is very time consuming, e.g. it takes 4 days to reach 10 7 cycles and more than 1 year for 10 9 cycles with conventional frequency of 30 Hz via a servohydraulic system. This limits the VHCF research and hence the VHCF behavior is still rarely studied for metallic materials with a designed microstructure, such as GS, heterogeneous, hierarchical, etc. Thus, whether the VHCF fatigue propert...

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Section: Methodsmentioning

confidence: 99%

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy

Pan

Qian

et al. 2020

Sci Rep

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“…Here, our focus is not on topology optimization 122 , but on mesoscale optimization of the spatial distribution of microstructure features 123 . In cases where processing is feasible, grading of structure or composition can enhance properties [124][125][126][127] , enabling lightweighting. Materials designers have explored gradients of grain size 124,[127][128][129] , twin density 130,131 , component or phase fraction 132 .…”

Section: Energy Efficiency By Lightweighting and Harsh Operating Condmentioning

confidence: 99%

“…In cases where processing is feasible, grading of structure or composition can enhance properties [124][125][126][127] , enabling lightweighting. Materials designers have explored gradients of grain size 124,[127][128][129] , twin density 130,131 , component or phase fraction 132 . These investigations demonstrated that the underlying physical micro-mechanisms of deformation can be influenced by such grading, leading to improvements in plasticity 133,134 , strengthening 135 , and damage resistance 124,127,130,131,136 .…”

Section: Energy Efficiency By Lightweighting and Harsh Operating Condmentioning

confidence: 99%

“…Materials designers have explored gradients of grain size 124,[127][128][129] , twin density 130,131 , component or phase fraction 132 . These investigations demonstrated that the underlying physical micro-mechanisms of deformation can be influenced by such grading, leading to improvements in plasticity 133,134 , strengthening 135 , and damage resistance 124,127,130,131,136 . However, processes that realize gradients are difficult to scale up (for example, accumulative roll bonding 137,138 , thin film deposition 139,140 ).…”

Section: Energy Efficiency By Lightweighting and Harsh Operating Condmentioning

confidence: 99%

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Strategies for improving the sustainability of structural metals

Raabe

Taşan

Olivetti

2019

Nature

375

143

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Metagoods 16% Vehicles 13% Industrial equipment 16% Construction 55% Re ne Smelter Mine Fabrication Manufacture Use New Scrap Old Scrap Land ll Carbon scrap/nickel to other scrap markets Stock End-of-life products c Transportation 19% Electronics 5% Chemicals 1% Industrial machinery 30% Household appliances and metal goods 28% Building and infrastructure17% Mine Rutile Mill product Ti ingot Manufacturing scrap Mill scrap End-of-life products Use Ferrotitanium Ti sponge TiO 2 feed TiCl 4

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“…Fatigue lives, even tested under one stress level, are always with larger scatter due to the uncertainty of material quality from the randomness of microstructure, surface and internal defects, and so on . A phenomenon shown in Figure has been found by large number of experiments that under the same loading condition, a specimen with higher quality often leads to a longer fatigue life, while a lower quality specimen leads to a shorter fatigue life, no matter at the high stress level or the low stress level …”

Section: Conversion Of Equivalent Fatigue Livesmentioning

confidence: 99%

New method for determining P‐S‐N curves in terms of equivalent fatigue lives

Bai

Peng

Zhang

et al. 2019

Fatigue Fract Eng Mat Struct

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A new method for determining the P‐S‐N curves is proposed by the probabilistic analysis of the mixed samples that are composed of the testing fatigue lives and equivalent fatigue lives. The equivalent fatigue lives at each level are converted from all the testing data at all the testing levels according to the equivalent fatigue failure probability, where the life distributions are determined by the medians of logarithmic fatigue lives at respective levels and a unified coefficient of variation. Comparison results of the P‐S‐N curves of 2024‐T3 and A356.0‐T6 alloys with the different methods indicate that the new method can determine the high‐precision P‐S‐N curves with different sample sizes of the S‐N testing data, and can save testing time and improve testing efficiency, especially for the situation of large‐scatter S‐N testing data.

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Improvement of low-cycle fatigue resistance in TWIP steel by regulating the grain size and distribution

Cited by 117 publications

References 67 publications

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy

Strategies for improving the sustainability of structural metals

New method for determining P‐S‐N curves in terms of equivalent fatigue lives

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