Fatigue Performance of Medical Ti6Al4V Alloy after Mechanical Surface Treatments

Abstract

Mechanical surface treatments have a long history in traditional engineering disciplines, such as the automotive or aerospace industries. Today, they are widely applied to metal components to increase the mechanical performance of these. However, their application in the medical field is rather rare. The present study aims to compare the potential of relevant mechanical surface treatments on the high cycle fatigue (R = 0.1 for a maximum of 10 million cycles) performance of a Ti6Al4V standard alloy for orthopedic, spinal, dental and trauma surgical implants: shot peening, deep rolling, ultrasonic shot peening and laser shock peening. Hour-glass shaped Ti6Al4V specimens were treated and analyzed with regard to the material’s microstructure, microhardness, residual stress depth profiles and the mechanical behavior during fatigue testing. All treatments introduced substantial compressive residual stresses and exhibited considerable potential for increasing fatigue performance from 10% to 17.2% after laser shock peening compared to non-treated samples. It is assumed that final mechanical surface treatments may also increase fretting wear resistance in the modular connection of total hip and knee replacements.

Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

“…It was prepared according to the procedure described elsewhere [69]. Such fabrication resulted in its improved mechanical properties [70]. Optimization Procedure for the SLM Samples A set of 26 cubic samples ( Figure 2) with a side length of 5 mm was fabricated in one batch on a Realizer SLM50 machine.…”

Enhanced fatigue behavior of powder metallurgy Ti–6Al–4V alloy by applying ultrasonic impact treatment

“…half of the UTS in compression; these compressive stresses are essentially larger than the baseline level of pristine material. It is well known that FWHM are useful to characterize the degree of work hardening present in mechanically surface treated materials [17,36,37], and it usually correlates well to the microhardness values. Essential growth of FWHM after the UIT process witnesses not only to the increase in dislocation density (surface hardening), but it also may indicate either some diminution in the crystallite size or the increase in the lattice micro-strains.…”

Influence of surface pre-treatments on the high-cycle fatigue behavior of Ti–6Al–4V – From anodizing to laser-assisted techniques

“…Still, these considerations are not able to explain the balanced fatigue properties of 19 the specimens processed by parameter set 2. As cracks are already present in the as-processed condition and the performance of these specimens is similar to the parameter set 1 at high stress levels, the similarly steep residual stress profile seems to be the most important factor.…”

“…Numerous factors have been shown to affect the fatigue behavior of metallic specimens and components, as discussed in [14][15][16][17][18][19][20][21]. In addition to microstructural features such as grain size, grain morphology, precipitates and phase fractions, geometrical factors such as specimen volume and shape have a strong impact.…”