Abstract
Laser shock peening of titanium alloys has been widely applied in the aerospace industry. However, little is known of the nanocrystalline formation characteristics and mechanisms. In this investigation, a nanocrystalline layer was formed in the duplex Ti-6Al-4V titanium alloy surface region by means of multiple pulsed laser shock peening (LSP). The phase transition and residual stress characteristics of LSP samples were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was used to characterize the microstructure and morphologies. As the number of laser pulses increased for each location, higher grain refinement was observed. Micro-hardness testing showed that hardness increased with the number of pulses delivered to each location due to the formation of nanocrystalline layers and high dislocation density in the samples, and a gradient variation of the micro-hardness was obtained. In addition, mechanical twins and different dislocation configurations were formed in the α phase region while only dense dislocation tangles were observed in the β phase region after multiple laser pulse impacts.
Highlights
Titanium alloys have extensive applications in the aerospace and medical industries because of their low density, high strength, and excellent corrosion resistance
Surface nanocrystallization [4,5] produced by severe plastic deformation (SPD) is the most effective and promising method to induce a nanocrystalline layer in bulk metallic materials and provides a practical approach to improving surface and overall properties of metallic materials
The severe plastic deformation induced by laser shock peening (LSP) could result in the increase of microstrain and microstrain and dislocation density in the material surface, which further contributed to grain dislocation density in the material surface, which further contributed to grain refinement
Summary
Titanium alloys have extensive applications in the aerospace and medical industries because of their low density, high strength, and excellent corrosion resistance. Tian et al [7] performed supersonic Fine Particle Bombarding (SFPB) on a Ti-6Al-4V alloy to form surface structures They found that the nano-grained surface exhibited a thick nitrogen diffusion layer and high hardness under the same nitriding process. Metals 2016, 6, 297 severe shot peening (SSP) to process 316L stainless steel Their results indicated that SSP transformed the austenite phase into a strain-induced α0 -martensite in a layered deformation band structure and induced near surface grain refinement to the nano and sub-micron range. The microstructure characteristics of different phases in the duplex Ti-6Al-4V alloy are of importance in understanding the grain refinement and surface nanocrystallization mechanism during LSP. A nanocrystalline layer on the surface of a bulk coarse-grained Ti-6Al-4V titanium alloy was formed via multiple LSP treatments. The microstructure characteristics of different phases in laser peened duplex Ti-6Al-4V alloy are discussed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
