The use of various peening methods to improve the fatigue strength of titanium alloy Ti6Al4V manufactured by electron beam melting

Hitoshi Soyama; Yuya Okura; Hitoshi Soyama; Yuya Okura

doi:10.3934/matersci.2018.5.1000

AIMS Materials Science

2018, Volume 5, Issue 5: 1000-1015. doi: 10.3934/matersci.2018.5.1000

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The use of various peening methods to improve the fatigue strength of titanium alloy Ti6Al4V manufactured by electron beam melting

Hitoshi Soyama ^,,
Yuya Okura

Department of Finemechanics, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan

Received: 21 August 2018 Accepted: 23 October 2018 Published: 29 October 2018

Additive manufacturing (AM) of metals is one of the foremost methods used for making medical implants and components for aviation. However, the fatigue strength of AM metals is weaker than that of the bulk equivalent. Mechanically treating the surface, such as by shot peening, can improve the fatigue strength, and novel peening methods without shot have also been proposed. In this paper, in order to demonstrate the improvements made in AM metals by various peening methods, specimens made of titanium alloy Ti6Al4V manufactured by electron beam melting (EBM) were treated by shot peening, laser peening and cavitation peening, then assessed by a plate bending fatigue test. In the case of shot peening, the shots were accelerated by a water jet to mitigate the incidence of dust during the process. For laser peening, the specimen was placed in water, and the effect of the impact produced at the target due to collapsing bubbles, which developed after laser ablation of the surface, was greater than the effect due to the laser ablation itself. For cavitation peening, the cavitation was generated by injecting a high speed water jet into water. In each case improvements in the fatigue strength of the Ti6Al4V were made. Improvements of 104% by laser peening, 84% by cavitation peening and 68% by shot peening compared with a non-peened specimen were achieved.
- mechanical surface treatment,
- medical implant,
- titanium alloy,
- additive manufacturing,
- electron beam melting,
- fatigue strength,
- shot peening,
- laser peening,
- cavitation peening
Citation: Hitoshi Soyama, Yuya Okura. The use of various peening methods to improve the fatigue strength of titanium alloy Ti6Al4V manufactured by electron beam melting[J]. AIMS Materials Science, 2018, 5(5): 1000-1015. doi: 10.3934/matersci.2018.5.1000

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Abstract

Additive manufacturing (AM) of metals is one of the foremost methods used for making medical implants and components for aviation. However, the fatigue strength of AM metals is weaker than that of the bulk equivalent. Mechanically treating the surface, such as by shot peening, can improve the fatigue strength, and novel peening methods without shot have also been proposed. In this paper, in order to demonstrate the improvements made in AM metals by various peening methods, specimens made of titanium alloy Ti6Al4V manufactured by electron beam melting (EBM) were treated by shot peening, laser peening and cavitation peening, then assessed by a plate bending fatigue test. In the case of shot peening, the shots were accelerated by a water jet to mitigate the incidence of dust during the process. For laser peening, the specimen was placed in water, and the effect of the impact produced at the target due to collapsing bubbles, which developed after laser ablation of the surface, was greater than the effect due to the laser ablation itself. For cavitation peening, the cavitation was generated by injecting a high speed water jet into water. In each case improvements in the fatigue strength of the Ti6Al4V were made. Improvements of 104% by laser peening, 84% by cavitation peening and 68% by shot peening compared with a non-peened specimen were achieved.

References

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