Fatigue Strength of Ti-35Nb-7Zr-5Ta

2012 ◽  
Vol 727-728 ◽  
pp. 73-79
Author(s):  
H. Alexander Franco ◽  
Cosme Roberto Moreira Silva ◽  
J.L.A. Ferreira ◽  
José A. Araújo
Keyword(s):  
Fatigue Strength ◽  
Grain Boundaries ◽  
Microstructural Analysis ◽  
Mean Stress ◽  
High Porosity ◽  
High Oxygen Content ◽  
Bending Fatigue ◽  
Four Point Bending ◽  
Ω Phase ◽  
Α Phase

Mean stress on fatigue strength of Ti-35Nb-7Zr-5Ta, used in the manufacture of orthopedic prostheses, was evaluates. Samples of Ti-35Nb-7Zr-5Ta were pressureless, sintered and tested using microhardness (Vickers) and four point bending fatigue conditions. Characterization was carried out using optical microscopy, scanning electron microscopy, EDS analysis, oxygen analysis and density. The microstructural analysis shows low densification after sintering (almost 86% of theoretical) and some precipitates of α phase and presumably ω phase at the grain and grain boundaries. The bending fatigue resistance limit reached (Se (106) = 90 MPa), due to, presumably, the influence of the medium-high porosity, α phase precipitates at grain boundaries as well as the high oxygen content in the material after sintering (0.96 %). In this case, Kwofie model best explains the influence of mean stress on fatigue strength of this alloy.

Influence of Heat Treatment on Fatigue Resistance of Sintered Ti 35Nb 7Zr 5Ta β Alloy

2014 ◽  
Vol 936 ◽  
pp. 1290-1297
Author(s):  
Alexander H. Franco ◽  
Cosme R.M. Silva ◽  
Palloma V. Muterlle ◽  
Jorge L.A. Ferreira ◽  
José A. Araújo
Keyword(s):  
Fatigue Strength ◽  
Grain Boundaries ◽  
Fatigue Resistance ◽  
Mean Stress ◽  
High Oxygen Content ◽  
Bending Fatigue ◽  
Four Point Bending ◽  
Α Phase ◽  
Density Analysis ◽  
Orthopedic Prosthesis

Mean stress on fatigue strength of Ti-35Nb-7Zr-5Ta, used in the manufacture of orthopedic prosthesis, was evaluated. Samples of Ti-35Nb-7Zr-5Ta were pressureless sintered and tested using microhardness (Vickers) and four point bending fatigue apparatus. Characterization was carried out using optical microscopy, scanning electron microscopy, EDS analysis, oxygen analysis and density. The density analysis shows almost 98% of density and microscopy reveals some precipitates of α phase and presumably ω phase at the grain and grain boundaries. The bending fatigue resistance limit reached (Se (106) 88 MPa), due to, presumably, the influence of coarse α phase precipitates at grain boundaries as well as the high oxygen content in the material after sintering (0.96 %). In this study, Kwofie model best explains the influence of mean stress on fatigue strength of this alloy.

Microstructural Analysis and Wear Behavior of Cryogenically Treated Ti-6Al-4V Alloy

2014 ◽  
Vol 592-594 ◽  
pp. 1331-1335 ◽  
Author(s):  
Haider Nasreen ◽  
S. Beer Mohamed ◽  
S. Rasool Mohideen
Keyword(s):  
Grain Boundaries ◽  
Wear Behavior ◽  
Cryogenic Treatment ◽  
Microstructural Analysis ◽  
Wear Loss ◽  
Β Phase ◽  
Α Phase ◽  
Treated Sample

This paper helps in understanding the effects of cryogenic treatment on microstructural variation, hardness and wear behavior of Ti-6Al-4V alloy. The microstructure indicates white β-phase dispersed on the grain boundaries of dark α-phase. Cryogenic treatment at-186 °C for 10 h led to the transformation from β-phase to α-phase, resulting in coarsening of α. Hardness of the cryogenically treated sample was observed to decrease and wear loss was observed to increase; this can be attributed to the coarsening of α-phase.

Bending Fatigue and Spring Back Properties of Implant Rods Made of β-Type Titanium Alloy for Spinal Fixture

2010 ◽  
Vol 89-91 ◽  
pp. 400-404 ◽  
Author(s):  
Kengo Narita ◽  
Mitsuo Niinomi ◽  
Masaaki Nakai ◽  
Toshikazu Akahori ◽  
Harumi Tsutsumi ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
The Other ◽  
Cycle Fatigue ◽  
Spring Back ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Four Point Bending ◽  
Bending Fatigue Strength

Implanting a spinal fixture using metallic rods is one of the effective treatments for spinal diseases. Because cyclic bending stress is loaded on the implant rods when patients move their upper bodies in daily life, bending fatigue properties are important for the implant rod. Further, the implant rods are bended plastically into a curved shape of spine by hand in a surgical operation. In that case, keeping shape is important, namely bending spring back properties are important factors. On the other hand, a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (mass %) alloy (TNTZ), has been developed by the authors. Currently, this alloy are investigated to be applied to the above mentioned implant rod practically. Therefore, four-point bending fatigue and three point-bending spring back properties of TNTZ subjected various heat treatments were examined in this study. TNTZ rods were subjected to solution treatment, and then some of them were subjected to aging treatment at 673 K or 723 K for 259.2 ks, followed by water quenching. Then, four-point bending fatigue and three-point bending spring back tests were carried out on TNTZ rods subjected to the various heat treatments mentioned above. The bending fatigue strength at 2.5 million cycles in the high cycle fatigue region are not much different among any TNTZ rod. However, the bending fatigue strength of the Ti-6Al-4V ELI (Ti64) rod exceeds the fatigue strengths of every TNTZ rods in both low and high cycle fatigue regions. On the other hand, the lower spring back, which is a favorable property, was obtained for some TNTZ rod than Ti64 rod.

High-resolution EM investigation about effect of stress on formation of ω-phase crystals in β-tttanium alloys

1996 ◽  
Vol 54 ◽  
pp. 1006-1007
Author(s):  
E. Sukedai ◽  
M. Shimoda ◽  
A. Fujita ◽  
H. Nishizawa ◽  
H. Hashimoto
Keyword(s):  
High Resolution ◽  
Titanium Alloys ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Zone Refining ◽  
Ω Phase ◽  
Α Phase ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Bcc Structure

ω-phase particles formed in β-titanium alloys (bcc structure) act important roles to their mechanical properties such as ductility and hardness. About the ductility, fine ω-phase particles in β–titanium alloys improve the ductility, because ω-phase crystals becomes nucleation sites of α-phase and it is well known that (β+α) duplex alloys have higher ductility. In the present study, the formation sites and the formation mechanism of ω-phase crystals due to external stress and aging are investigated using the conventional and high resolution electron microscopy.A β-titanium alloy (Til5Mo5Zr) was supplied by Kobe Steel Co., and a single crystal was prepared by a zone refining method. Plates with {110} surface were cut from the crystal and were pressured hydrostatically, and stressed by rolling and tensile testing. Specimens for aging with tensile stress were also prepared from Ti20Mo polycrystals. TEM specimens from these specimens were prepared by a twin-jet electron-polishing machine. A JEM 4000EX electron microscope operated at 400k V was used for taking dark field and HREM images.

Four Point Bending Fatigue Tests of Forged Ti 6Al 4V

2009 ◽  
Vol 51 (9) ◽  
pp. 580-586 ◽  
Author(s):  
Bernd Oberwinkler ◽  
Martin Riedler ◽  
Heinz Leitner ◽  
Ataollah Javidi
Keyword(s):  
Fatigue Tests ◽  
Bending Fatigue ◽  
Four Point Bending

scholarly journals On the determination of the bending fatigue strength in and above the very high cycle fatigue regime of shot-peened gears

2021 ◽  
Author(s):  
D. Fuchs ◽  
S. Schurer ◽  
T. Tobie ◽  
K. Stahl
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Load Carrying Capacity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Very High Cycle Fatigue ◽  
Bending Load ◽  
Load Carrying ◽  
Bending Fatigue Strength ◽  
Very High

AbstractDemands on modern gearboxes are constantly increasing, for example to comply with lightweight design goals or new CO2 thresholds. Normally, to increase performance requires making gearboxes and powertrains more robust. However, this increases the weight of a standard gearbox. The two trends therefore seem contradictory. To satisfy both of these goals, gears in gearboxes can be shot-peened to introduce high compressive residual stresses and improve their bending fatigue strength. To determine a gear’s tooth root bending fatigue strength, experiments are conducted up to a defined number of load cycles in the high cycle fatigue range. However, investigations of shot-peened gears have revealed tooth root fracture damage initiated at non-metallic inclusions in and above the very high cycle fatigue range. This means that a further reduction in bending load carrying capacity has to be expected at higher load cycles, something which is not covered under current standard testing conditions. The question is whether there is a significant decrease in the bending load carrying capacity and, also, if pulsating tests conducted at higher load cycles—or even tests on the FZG back-to-back test rig—are necessary to determine a proper endurance fatigue limit for shot-peened gears. This paper examines these questions.

scholarly journals Effects of Double-Ageing Heat Treatments on the Microstructure and Mechanical Behaviour of a Ti-3.5Al-5Mo-4V Alloy

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 209
Author(s):  
Xuanming Ji ◽  
Panpan Ge ◽  
Song Xiang ◽  
Yuanbiao Tan
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Mechanical Behaviour ◽  
Ageing Time ◽  
Two Stage ◽  
Ageing Treatment ◽  
Ω Phase ◽  
Α Phase ◽  
Temperature Ageing

In this work, the effect of double-ageing heat treatments on the microstructural evolution and mechanical behaviour of a metastable β-titanium Ti-3.5Al-5Mo-4V alloy is investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-ageing treatments are composed of low-temperature pre-ageing and high-temperature ageing, where the low-temperature pre-ageing is conducted at 300 °C or 350 °C for different times, and the high-temperature ageing is conducted at 500 °C for 8 h. The results show that the phase transformation sequence is altered with the time spent during the first ageing stage, the isothermal ω phase is precipitated in the pre-ageing process of the alloy at 300 °C and 350 °C with the change in the ageing time, and the ω phase is finally transformed into the α phase with the extension of pre-ageing time. The existence time of the ω phase is shortened as the pre-ageing temperature increases. The microhardness of the alloy increases with increasing pre-ageing time and temperature. Compared with single-stage ageing, the ω phase formed in the pre-ageing stage changes the response to subsequent high-temperature ageing. After the two-stage ageing treatment, the precipitation size of the α phase is obviously refined after the double-ageing treatment. A microhardness test shows that the microhardness of the two-stage aged alloy increases with extended pre-ageing time.

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