Deep rolling of titanium rods for application in modular total hip arthroplasty

Abstract

Compressive residual stresses are commonly introduced into the near-surface regions of morse taper junctions of modular hip endoprostheses to prolong fatigue life. An increasing number of publications report that contamination of shot-peened surfaces can lead to enhanced corrosion and third body wear. This study evaluates deep rolling of titanium alloy rods as a possible alternative to shot peening. Ten rods of Ti6Al7Nb alloy with a diameter of 15 mm were deep rolled with various rolling parameters. The resulting surface topography and residual contamination was analyzed using a scanning electron microscope (SEM). The near-surface residual stress states after deep rolling were characterized by means of X-ray diffraction. The roughness of the surfaces before deep rolling was about R(z) = 14 microm, and after deep rolling surface roughness values of R(z) 0.4-7.5 microm were achieved. The results of the SEM and EDAX analyses of the sample surface showed no evidence of surface contamination by particles or abrasion products caused by any process. At a pressure of 300 bar, compressive stress reached the maximum of -1150 MPa at a depth of 0.1 mm. Deep rolling thus allows a smooth and particle-free surface to be obtained and therefore shows promise as a surface treatment for mating surfaces of morse tapers in modular hip endoprostheses.

Fatigue Performance of Medical Ti6Al4V Alloy after Mechanical Surface Treatments

“…Thus, the final shot peening process using glass beads that have been applied subsequently to the shot peening by cut wire and the laser shock peening may be one option for cleaning when it is guaranteed that glass contamination is minimized to avoid increased wear due to hard foreign particles (third body wear) [ 39 , 40 ]. Deep rolling was proposed as a suitable alternative to the peening treatment on a medical grade Ti6Al7Nb alloy resulting in beneficial residual stress depth distributions with its maximum of compressive residual stresses below the surface and no contaminations at the surface [ 29 ]. However, since the basic loading mode of the hip junction is bending, the highest compressive residual stresses are expected to minimize crack initiation at the very surface.…”

“…This is certainly the reference material for further developments, such as new titanium based alloys or carbon fiber reinforced PEEK [ 27 ]. (d) Final surface modifications : beside thermal treatments, mechanical surface treatments enhance the fatigue and cyclic deformation behavior of titanium alloys and have already been applied in parts within the scope of biomedical applications [ 28 , 29 ]. From other engineering disciplines, they are known to strengthen the substrate without changing the material’s composition [ 30 ].…”

“…This is why most implant manufacturers do not have direct access to this technology. However, there are some revision hip replacement systems which are put under a final shot peening or deep rolling step in the manufacturing process [ 28 , 29 ]. Therefore the aim of this study was to give a substantial and practical overview and comparison on relevant mechanical treatments for medical applications of the titanium standard alloy, Ti6Al4V, in terms of fatigue strengths.…”

Biodegradable Orthopedic Magnesium-Calcium (MgCa) Alloys, Processing, and Corrosion Performance

“…Denkena et al [12] tried to control the corrosion of the Mg-Ca3.0 implant by mechanical treating the implant surface using DR technique and ultimately to achieve adaptable degradation profile for various medical applications. As compared to shot peening, LPB/DR avoids the contamination of the processed surfaces and consequently prevents the third body wear [53]. Besides, LPB/DR produces higher and deeper compressive residual stresses with less amount of clod work [49,54].…”

Effect of Slide Burnishing on the Surface Layer and Fatigue Life of Titanium Alloy Parts

“…For example, after the rolling burnishing of Ti-2.5Cu alloy, a strain-hardened layer was obtained, which was about 3 times deeper than the layer produced by shot peening [13]. Effects of roller burnishing depend to a large extent on technological conditions, as confirmed by the investigation of TiAl6Nb7 alloy [14] and tool design [15]. The authors of the study [16] have found that the combined use of roller burnishing and nitriding on the samples made of titanium alloy Ti-6Al-5Mo-5V-1, 5Cu-1Fe (according to Russian standards VT22) leads to higher wear resistance of these samples in contact with Cu-10Al-4Ni-4Fe counter-samples.…”