Effect of dynamic recrystallization on texture orientation and grain refinement of Ti6Al4V titanium alloy subjected to laser shock peening

In order to increase the vibration life of Ti6Al4V titanium alloy, warm laser shock peening (WLSP) is used to improve the damping properties and thus decrease the vibration stress in this study. Firstly, the Ti6Al4V specimens are treated by WLSP at different treatment temperatures from 200 °C to 350 °C. Then the damping ratios of untreated and WLSPed samples are obtained by impact modal tests, and the improvement of damping properties generated byWLSP is analyzed by the microstructures in Ti6Al4V titanium alloy. Moreover, the finite element simulations are utilized to study the vibration amplitude and stress during the frequency response process. Finally, the vibration fatigue tests are carried out and the fatigue fracture morphology is observed by the scanning electron microscope. The results indicate that the damping ratios of WLSPed specimens increase with the increasing treatment temperatures. This is because elevated temperatures during WLSP can effectively increase the α phase colonies and the interphase boundaries, which can significantly increase the internal friction of materials. Moreover, due to the increasing material damping ratio, the displacement and stresses during vibration were both reduced greatly by 350 °C-WLSP, which can significantly decrease the fatigue crack growth rate and thus improve the vibration fatigue life of Ti6Al4V titanium alloy.

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Laser shock peening of laser additive manufactured Ti6Al4V titanium alloy

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2018.06.020 ◽

2018 ◽

Vol 349 ◽

pp. 503-510 ◽

Cited By ~ 39

Author(s):

Wei Guo ◽

Rujian Sun ◽

Binwen Song ◽

Ying Zhu ◽

Fei Li ◽

...

Keyword(s):

Titanium Alloy ◽

Laser Shock Peening ◽

Laser Shock ◽

Ti6al4v Titanium Alloy ◽

Shock Peening

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Effects of Laser Shock Peening on Microstructure and Properties of Ti–6Al–4V Titanium Alloy Fabricated via Selective Laser Melting

Materials ◽

10.3390/ma13153261 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3261

Author(s):

Liang Lan ◽

Ruyi Xin ◽

Xinyuan Jin ◽

Shuang Gao ◽

Bo He ◽

...

Keyword(s):

Mechanical Properties ◽

Residual Stress ◽

Titanium Alloy ◽

Grain Refinement ◽

Selective Laser Melting ◽

Laser Shock Peening ◽

Laser Shock ◽

Laser Melting ◽

Α Phase ◽

Shock Peening

Laser shock peening (LSP) is an innovative surface treatment process with the potential to change surface microstructure and improve mechanical properties of additively manufactured (AM) parts. In this paper, the influences of LSP on the microstructure and properties of Ti–6Al–4V (Ti64) titanium alloy fabricated via selective laser melting (SLM), as an attractive AM method, were investigated. The microstructural evolution, residual stress distribution and mechanical properties of SLM-built Ti64 samples were characterized before and after LSP. Results show that the SLM sample was composed of single hcp α’ phase, which deviates from equilibrium microstructure at room temperature: α + β phases. The LSP significantly refines the grains of α’ phase and produces compressive residual stress (CRS) of maximum magnitude up to −180 MPa with a depth of 250 μm. Grain refinement of α’ phase is attributed to the complex interaction of dislocations and the intersection of deformation twinning subjected to LSP treatment. The main mechanism of strength and micro-hardness enhancement via LSP is ascribed to the effects of CRS and α’ phase grain refinement.

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