Fatigue properties of a new generation ß-type Ti-Nb alloy for osteosynthesis with an industrial standard surface condition

Reck, André; Pilz, Stefan; Calin, Mariana; Gebert, A.; Zimmermann, Martina

doi:10.1016/j.ijfatigue.2017.05.024

Cited by 6 publications

(12 citation statements)

References 27 publications

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“…3 with results of a previous study of Ti-40Nb-Rk samples with the same geometry and test conditions [36] but with laser cut surface a remarkable increase of fatigue strength from σ a = 150 MPa (laser cut surface) to σ a = 225 MPa (mechanically polished surface) is apparent. The effect introduced by the laser cut surface can be determined by a notch factor K f of 1.5.…”

Section: Fatigue Resultssupporting

confidence: 79%

“…Either local heat development during laser processing or applied residual compression stresses from the mechanical polishing could result in the activation of the phase transformation, due to the high metastable character of this alloy condition. Special relevance obtains this result considering the high importance of laser processing for implant materials in automatized industrial process chains [36].…”

Section: Microstructure and Phase Investigationsmentioning

confidence: 94%

“…(β)-Ti-40Nb sheet samples were laser-cut in agreement with our previous study [36]. Recrystallized samples, afterwards called Ti-40Nb-Rk, and aged samples with omega ω-precipitations, afterwards called Ti-40Nb-Om4h were subsequently stepwise mechanically polished (Grit 2500) to remove the thin oxide layer from the heat treatment and to minimize surface roughness related notch influences and the heat affected zone (HAZ)) from the laser cutting [36]. (β)-Ti-45Nb rods were turned to the given geometry (Fig 1b) and also mechanically polished to Grit 2500.…”

Section: Alloy Processing and Machiningmentioning

confidence: 97%

“…Comparisons will be drawn to a previous study focusing on the notch effect due to an industrial surface condition of the same alloy [36]. Furthermore commercially available (β)-Ti-45(wt%)Nb was studied to comprehend influences of Nb-content and first invitro tests are carried out to assess corrosion fatigue.…”

Section: Introductionmentioning

confidence: 99%

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Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

et al. 2018

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Abstract. This study examined the fatigue properties of a newly developed cast and thermomechanical processed (β)-Ti-40Nb alloy for a possible application as biomedical alloy due to exceptional low Young's modulus (64-73 GPa), high corrosion resistance and ductility (20-26%). Focusing on the influence of two microstructural states with fully recrystallized β-grain structure as well as an aged condition with nanometer-sized ω-precipitates, tension-compression fatigue tests (R=-1) were carried out under lab-air and showed significant differences depending on the β-phase stability under cyclic loading. Present ω-precipitates stabilized the β-phase against martensitic α'' phase transformations leading to an increased fatigue limit of 288 MPa compared to the recrystallized state (225 MPa), where mechanical polishing and subsequent cyclic loading led to formation of α''-phase due to the metastability of the β-phase. Additional studied commercially available (β)-Ti-45Nb alloy revealed slightly higher fatigue strength (300 MPa) and suggest a change in the dominating cyclic deformation mechanisms according to the sensitive dependence on the Nb-content. Further tests in simulated body fluid (SBF) at 37°C showed no decrease in fatigue strength due to the effect of corrosion and prove the excellent corrosion fatigue resistance of this alloy type under given test conditions.

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Section: Fatigue Resultssupporting

confidence: 79%

Section: Microstructure and Phase Investigationsmentioning

confidence: 94%

Section: Alloy Processing and Machiningmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

et al. 2018

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“…However, the thermal input due to the laser must be adjusted and optimized regarding the surface roughness and resulting heat-affected zone (HAZ). Otherwise, microand macro-notch effects can negatively affect the fatigue behavior leading to catastrophic pre-mature failure in their application [4,[10][11][12]. The local changes of the microstructure in the HAZ may also have a significant influence on the mechanical properties and on the fatigue strength, in particular [4,[13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

Reck

Zeuner

Zimmermann

2019

Metals

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The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength.

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Influence of Swaging on Microstructure, Elastic Modulus and Vickers Microhardness of β Ti-40Nb Alloy for Implants

Santos

Ricci

Afonso

2021

J. of Materi Eng and Perform

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Fatigue properties of a new generation ß-type Ti-Nb alloy for osteosynthesis with an industrial standard surface condition

Cited by 6 publications

References 27 publications

Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

Influence of Swaging on Microstructure, Elastic Modulus and Vickers Microhardness of β Ti-40Nb Alloy for Implants

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