Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl Żebrowski r, wAlczAk M, klepkA T, pAsierbiewicz k. effect of the shot peening on surface properties of Ti-6Al-4V alloy produced by means of DMls technology. eksploatacja i Niezawodnosc -Maintenance and reliability 2019; 21 ( 1): 46-53, http://dx.doi.org/10.17531/ ein.2019.1.6. remigiusz Żebrowski Mariusz wAlczAk Tomasz klepkA kamil pAsierbiewicz EffEct of thE shot pEEning on surfacE propErtiEs of ti-6al-4V alloy producEd by mEans of dmls tEchnology WpłyW nagniatania strumiEnioWEgo na WłaściWości EksploatacyjnE stopu ti-6al-4V uzyskanEgo tEchnologią przyrostoWą dmls* The state of the surface layer and biocompatibility are the key parameters contributing to successful implantation of prostheses such as bone implants which are now increasingly often produced by means of DMLS technologies. The analysis of these factors and proper selection of material are required in order to determine the most favourable technological parameters contributing to long term functioning in course of their presence in human body. Therefore, the purpose of the present paper is to investigate the effect of shot peening on the state of the surface layer and corrosion resistance of specimens made of Ti-6Al-4V titanium alloy produced in Direct Metal Laser Sintering (DMLS) process. The specimens have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders and their surfaces have been subjected to the shot peening process under three different working pressures (0.2, 0.3 and 0.4 MPa) and by means of three different media i.e. CrNi steel shot, crushed nut shells and ceramic balls based on ZrO 2 . It has been found that the process conditions i.e. working pressure in course of shot peening and proper selection of applied shot will make it possible to achieve the properties in modified material sufficient to ensure that assumed functions associated with the improvement of surface layer condition are invariable during required period in specified implant operation conditions. In such case, these factors have been determined in course of microhardness tests, evaluation of surface development degree as well as potentiodynamic tests. The increase of working pressure caused deteriorated corrosion resistance. Simultaneously, it has been found the corrosion resistance was most satisfactory for the surfaces modified by means of: ceramic balls based on ZrO 2 > crushed nut shells > CrNi steel shot correspondingly.

Structural discontinuities characterize the implants produced directly from metal powders in 3D printing technology. Mainly, the surface defects should be subjected to procedures associated with surface layer modification (likewise shot peening) resulting in the increase of the implant service life maintaining optimal biocompatibility. Therefore, the purpose of the present study was to investigate the effect of type of shot used for the peening process on the Ti-6Al-4V implants functional properties as well as the biological properties. The components were produced by DMLS (direct metal laser sintering) additive technology. The surfaces of titanium specimens have been subjected to the shot peening process by means of three different shots, i.e., CrNi steel shot, crushed nut shells, and ceramic balls shot. Then, the specimens have been subjected to profilometric analysis, microhardness tests, and static strength testing as well as to the assessment of biocompatibility in respect of cytotoxicity using human BJ fibroblasts. The shot peening process causes the strengthening of surface layer and the increase of strength parameters. Furthermore, the test results indicate good biocompatibility of surfaces being tested, and the effect of shot peening process on the titanium alloy cytotoxicity is acceptable. At the same time, most favourable behaviour in respect of cytotoxicity has been found in the case of surfaces modified by means of ceramic balls > nut shells > CrNi steel shot correspondingly.

Additive Manufacturing processes are being used increasingly in the scope of medicine and dentistry. As indicated by literature data, the durability and quality of medical implants is decisively influenced by surface modification. Insufficient quality of surface finishing leads, among others, to reduced service life of applied implants and to increased number of necessary revision surgeries. Furthermore, various types of finishing processes e.g. cleaning, shot peening or abrasive techniques are suggested by the manufacturers of products made by means of DMLS processes. Due to this fact, the analysis of proper formation of the surface layer of titanium products made by means of the method consisting in the direct laser sintering of metal powders (DMLS) was the subject matter of our research. Therefore, Ti-6Al-4V titanium alloy has been used for tests. The samples have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders. The surfaces of prepared samples have been subjected to shot peening process at three different values of working pressure (0.2, 0.3 and 0.4 MPa) by means of three different working media i.e. CrNi steel shot, crushed nut shells and ceramic balls. The characteristics of the materials used for shot peening process have been determined by means of Zeiss Ultra Plus scanning electron microscope. The samples have been subjected to profilometric measurements on Bruker Contour GT optical profilometer and the corrosion behaviour of Ti-6Al-4V titanium alloy in Ringer solution has been determined in electrode impedance spectroscopy (EIS) measurements by means of Atlas 0531 set dedicated for corrosion testing. The overall results of all tests indicate to favourable influence of the shot peening process on the corrosion behaviour of titanium alloy.

Objective. The aim the study was to investigate the impact of the shot peening process on the condition of the surface layer and biological properties of titanium alloy produced by means of the Direct Metal Laser Sintering (DMLS) method. Materials and method. Specimens were prepared by the EOSINT M280 metal sintering laser system. The surfaces were subjected to the shot peening process using three different media, i.e. steel shot, nutshell granules and ceramic beads, after which they were subjected to profilometric analysis, scanning electron microscopic (SEM) observations and energy dispersive X-ray spectroscopy (EDS) tests, as well as to assessment of biological compatibility in terms of cytotoxicity (SH-SY5Y cell lines). Results. The general results obtained from the tests indicate satisfactory biocompatibility of the examined surfaces and that the impact of the shot peening process on the titanium alloy cytotoxicity is acceptable. Conclusions. The lowest cytotoxicity was demonstrated by the surfaces modified by ceramic beads than the nutshells and the biggest steel shot correspondingly. Moreover, the shot peening process carried out by means of CrNi steel and ceramic shot caused the reduction of surface roughness when, for the surface processing by means of nutshell granules, the increase of surface roughness was observed compared with the unmodified surface of titanium alloy samples.

The purpose of the present paper was to investigate the effect of shot peening on the condition of the surface layer and abrasion resistance of specimens made of Ti-6Al-4V titanium alloy produced by Direct Metal Laser Sintering (DMLS) process. The specimens have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders and their surfaces have been subjected to the shot peening process under three different working pressures (0.2, 0.3 and 0.4 MPa) and by means of three different media i.e. CrNi steel shot, crushed nut shells and ceramic balls. The specimens have been subjected to profilometric analysis, to SEM examinations, microhardness tests and to tribological tests on ball-on-disc stand in Ringer fluid environment. The general results of all tests indicate to favourable effect of shot peening process on the hardness and tribological performance of titanium alloy.