Fatigue behavior of Ti6Al4V and 316 LVM blasted with ceramic particles of interest for medical devices.
Grit blasting is used as a cost-effective method to increase the surface roughness of metallic biomaterials, as Ti6Al4V and 316 LVM, to enhance the osteointegration, fixation and stability of implants. Samples of these two alloys were blasted by using alumina and zirconia particles, yielding rough (up to Ra~8μm) and nearly smooth (up to Ra~1μm) surfaces, respectively. In this work, we investigate the sub-surface induced microstructural effects and its correlation with the mechanical properties, with special emphasis in the fatigue behavior. Blasting with zirconia particles increases the fatigue resistance whereas the opposite effect is observed using alumina ones. As in a conventional shot penning process, the use of rounded zirconia particles for blasting led to the development of residual compressive stresses at the surface layer, without zones of stress concentrators. Alumina particles are harder and have an angular shape, which confers a higher capability to abrade the surface, but also a high rate of breaking down on impact. The higher roughness and the presence of a high amount of embedded alumina particles make the blasted alloy prone to crack nucleation. Interestingly, the beneficial or detrimental role of blasting is more intense for the Ti6Al4V alloy than for the 316 steel. It is proposed that this behavior is related to their different strain hardening exponents and the higher mass fraction of particles contaminating the surface. The low value of this exponent for the Ti6Al4V alloy justifies the expected low sub-surface hardening during the severe plastic deformation, enhancing its capability to soft during cyclic loading.
Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo n° 8, 28040 Madrid, Spain.
S
S
Barriuso
Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo n° 8, 28040 Madrid, Spain.
J
J
Chao
Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo n° 8, 28040 Madrid, Spain.
J A
JA
Jiménez
Surgival, SL, Valencia, Spain.
S
S
García
Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo n° 8, 28040 Madrid, Spain; Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain. Electronic address: jlg@cenim.csic.es.
J L
JL
González-Carrasco
D000497:Alloys; D000537:Aluminum Oxide / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D019245:Compressive Strength; D004864:Equipment and Supplies; D008422:Materials Testing; D013193:Stainless Steel / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry
D000497:Alloys; D001672:Biocompatible Materials; D013193:Stainless Steel; C031462:titanium alloy (TiAl6V4); D015040:Zirconium; D014025:Titanium; D000537:Aluminum Oxide; C028541:zirconium oxide
316 LVM; Biomaterials; Fatigue strength; Grit blasting; Mechanical behavior; Ti6Al4V