The Very High Cycle Fatigue Behaviour of Ti-6Al-4V Alloy

Abstract

The high cycle and very high cycle fatigue properties of the titanium alloy Ti6Al4V with a duplex microstructure were investigated at room temperature. High cycle fatigue tests were performed in the range from 10 4 to 10 7 cycles by rotating bending at the frequency of 30 Hz. The very high cycle fatigue tests were carried out in the range from 10 7 to 10 10 cycles in tension-compression on an ultrasonic fatigue testing machine at the frequency of 20 kHz. The stress amplitude was found to decrease with increasing number of cycles in the whole range from 10 4 up to 10 9 cycles and only at the highest number of cycles (NF = 10 9 ) the alloy exhibits the fatigue limit of 460 MPa. The detail fractographic analysis was performed to characterize the fatigue failure mechanisms. Both subsurface and surface crack initiation were observed in very high cycle fatigue region. No inclusions, but only local chemical inhomogeneity in microstructure was observed at the locations of subsurface fatigue crack initiation in alpha-grains.

Crack initiation in VHCF regime on forged titanium alloy under tensile and torsion loading modes

“…Thus, we can say that forged VT3-1 does not show a horizontal asymptote like many others structural materials [8] and there is no infinite fatigue life [16,17]. A similar result has been reported for Ti-6Al-4V titanium alloy by Janecek [18] in VHCF regime under fully-reversed loading (R = À1) at 20 kHz. It has been stated that the SN curves exhibit a continuous decrease of the stress amplitude with increasing number of cycles from 10 4 to 10 9 cycles.…”

“…In our experiments the analysis of the fracture surfaces has shown two principal crack initiation locations: surface and subsurface. This result is common for two-phase titanium alloy and was already reported for different alloy [18,19]. However, in order to understand the reason of so large scatter of the fatigue life (Fig.…”

Adhesion and Mechanical Properties of TiAlN and AlTiN Magnetron Sputtered Coatings Deposited on the DMSL Titanium Alloy Substrate

“…Moreover, they intensify pain and negative biological response of tissues which leads to local irritation and inflammation and consequently, to implant failure. Titanium and its alloys are very popular in medicine although the cobalt based and nickel based alloys are still applicable as a biomaterials [1][2][3][4][5][6][7]. Unfortunately, titanium alloys have insufficient abrasion resistance.…”

“…Nitride layers formation technology using the PVD methods is popular in the processes for * corresponding author; e-mail: m.szala@pollub.pl improving the properties of biomaterials or machining tools. Unfortunately, reports in the literature indicate that the films are usually deposited on the bulk metal substrates [4,6,[8][9][10][11][12] or the cemented carbides substrates [8,13,14]. Moreover, the literature survey indicates that there are no reports regarding morphology, mechanical properties, and adhesion of coatings of AlTiN and TiAlN deposited on the DMLS titanium-based substrates.…”

Additive manufacturing and mechanical properties of titanium lattices for biomedical applications

“…However, the majority of the studies that involved TPMS [77,244,245] have only used quasi-static compression tests as a means to justify structural integrity. But in reality, an implanted material will be subject to a high number of cycles through its life time [246] and will be frequently loaded in tension. This is why it is crucial to take into consideration the high cycle fatigue life behaviour of these materials, and in particular tension-tension fatigue, when developing a new generation of metallic biomaterials.…”