Effect of strain amplitude on low cycle fatigue and microstructure evolution in Ti-6Al-4V: A TKD and TEM characterization

Jha, Jyoti S.; Dhala, Satyabrata; Toppo, Suraj P.; Singh, Rajeev Kumar; Tewari, Ashish; Mishra, Sushil; Jayabalan, Bhagyaraj

doi:10.1016/j.matchar.2019.109829

Cited by 37 publications

(5 citation statements)

References 39 publications

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“…Yang et al 35 found that for some ductile materials the elastic modulus decreases according to the increase of plastic strain is due to the movable dislocation accompanying the pile-up of dislocations near to the grain boundary. This behavior was also observed by Jha et al 36 in LCF tests in an annealed titanium alloy Ti6Al4V obtained by conventional processes. These authors observed the formation of slip band, hexagonal network and sub-grain boundary using a transmission electron microscope (TEM) and transmission Kikuchi diffraction (TKD).…”

Section: Strain-life Curvessupporting

confidence: 83%

Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

Jesús

Borrego

Ferreira

et al. 2021

Fatigue Fract Eng Mat Struct

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Fatigue behavior (R ε = −1) of HIPed and stress relieved Ti6Al4V alloy specimens produced by selective laser melting (SLM) was analyzed and compared resulting that the hot isostatic pressing (HIP) process caused a microstructural transformation decreasing the hardness and monotonic properties leading to cyclic softening that not allowed fatigue strength to increase. A bilinear behavior in the elastic strain-fatigue life curve was observed due to the decrease of the Young's modulus during the cyclic elastoplastic tests, consequence of subgrains formation. The Smith-Watson-Topper and total strain energy density models adjusted by the bilinear behavior showed a good concordance between predicted and experimental fatigue lives in notched samples.

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Section: Strain-life Curvessupporting

confidence: 83%

Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

Jesús

Borrego

Ferreira

et al. 2021

Fatigue Fract Eng Mat Struct

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“…1c, d) the α-phase was transformed into Widmanstätten needles (in the case of AC) or martensitic α′-phase with needle morphology (in the case of WQ). These changes in the microstructure have a significant effect on the mechanical properties, especially on the course of microhardness from the surface, through the alpha-case layer into the core of the material and on the fatigue characteristics of the alloy [12,14,15]. The course of the microhardness change HV0.2/10 is show in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Feng et al [9], Dong et al [10] and Taxier et al [11], results show that the increasing thickness of the alpha-case layer does not significantly reduce the high-temperature plasticity of the Ti6Al4V alloy, but mainly the mechanism of failure changes from ductile to brittle failure. The formation of the alpha-case layer concerning the formation and propagation of fatigue cracks was investigated by Jha et al [12], Seth et al [4], Littlewood and Wilkinson [13] and Belan et al [14]. It follows from the above works that the formation of the alpha-case layer significantly reduces the fatigue life of the alloy and fatigue cracks are initiated from microcracks formed in the alpha-case layer.…”

Section: Introductionmentioning

confidence: 99%

Formation of Alpha-Case Layer during Oxidation of Ti6Al4V Surface by Annealing at 1050 °C and Change of Microstructure after Different Cooling Rates

Belán

Uhríčik

Kuchariková

et al. 2023

MSF

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The two-phase titanium alloy Ti6Al4V (often referred to as GRADE 5 or Ti64) is currently probably the most widely used type of Ti alloy. It is characterized by an excellent combination of strength - toughness - chemical stability. However, at temperatures above 500 - 800 °C it is prone to the diffusion of oxygen into surface layers, where the increased oxygen content creates the so-called “alpha-case” layer. The formation of this layer is associated with a reduction mainly in the deformation characteristics of the alloy. The paper focuses on the metallographic analysis of the "alpha-case" layer after annealing at 1050 °C with a holding time of 3 hours and cooling at different cooling rates (500 °C/s, 1 °C/s and 0.08 °C/s). Microstructure changes were observed by light microscopy using polarized light – PL, dark field – DF and phases were identified by SEM methods. The influence of changes in the microstructure on the mechanical properties was determined by measuring the microhardness HV0.2 /10 (STN EN ISO 6507) with Zwick / Roell ZHµ and measuring the resistance to impact stress KU (Charpy system STN EN 10045-1). Based on the microhardness measurement, an increase in the microhardness of the surface layers was observed at all cooling rates and at the same time, a decrease in the impact resistance was observed compared to the initial state.

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“…So, the micromechanical deformation behaviour in terms of crystallographic misorientation, GND and slip system activation due to the LCF was extensively studied in the literature. 40–45 In this work, the effect of variation in martensite fraction was studied with experimental and FE-simulated results of LCF behaviour through actual microstructure-based 2D RVE associated with the CP model considering alloy partitioning, solid solution strengthening and initial GND density of constituent phases.…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructural constituents and morphological characteristics on low cycle fatigue behaviour of inter-critically annealed 20MnMoNi55 steel

Basu

Acharyya

Sahoo

2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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The effect of varying microstructural parameters on the cyclic behaviour of dual-phase steels was studied on the basis of experimental and micromechanical finite-element simulated results. The initial bainitic morphology of as-received 20MnMoNi55 steel was transformed into ferrite and martensite through proper inter-critical heat treatment procedures. Strain-controlled low cycle fatigue tests were conducted at room temperature with different strain amplitudes at a specific strain rate of 10−3/s. The cyclic stress–strain curve, obtained through joining the peak stresses of hysteresis loops corresponding to different strain amplitude, shows an increase in strain hardening with an increase in volume fraction of martensite. Whereas the rate of cyclic softening, considering the decrease in stress amplitude with respect to elapsed cycles, increases with increasing strain amplitude. Inclusive of all affecting microstructural parameters, an original microstructure-based representative volume element associated with a crystal plasticity-based material model was adopted for conducting micromechanical finite-element simulation. In addition to several parameters associated with a crystal plasticity model, consideration of initial geometrically necessary dislocation density in constituent phases resulted in the accurate prediction of a hysteresis loop at low strain amplitude as compared with the experimental results. A variation of stress triaxiality built up in ferrite matrix with martensite fraction along with deformation inhomogeneity between ferrite and martensite was also observed through a strain partitioning phenomenon obtained from finite-element simulated results.

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Effect of strain amplitude on low cycle fatigue and microstructure evolution in Ti-6Al-4V: A TKD and TEM characterization

Cited by 37 publications

References 39 publications

Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

Formation of Alpha-Case Layer during Oxidation of Ti6Al4V Surface by Annealing at 1050 °C and Change of Microstructure after Different Cooling Rates

Effect of microstructural constituents and morphological characteristics on low cycle fatigue behaviour of inter-critically annealed 20MnMoNi55 steel

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