Abstract
High cycle fatigue failure of titanium alloy components on the aircraft is a serious problem that affects the flight safety. The low energy laser peening without coating (LPwC) has been demonstrated for the improved fatigue resistance of metallic materials via the introduction of compressive residual stress and microstructure modifications. Therefore, in the present study, LPwC with different impacts were conducted on the Ti-17 titanium alloy using the Mianna-Q laser with the wavelength of 532 nm and energy of 85 mJ. The surface and depth-wise residual stress and micro-hardness distributions were presented on the samples with and without LPwC treatment. High amplitude compressive residual stress was introduced, and the hardness was significantly improved. The microstructures of the Ti-17 samples after LPwC was characterized using the X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Furthermore, high cycle fatigue performance of the as-cast, LPwCed sample with 1 impact and LPwCed sample with 3 impacts was evaluated via the tension-compression fatigue test. The fatigue strength of the LPwCed specimen was increased from 390 to 475.4 MPa (1 impact) and 490.3 MPa (3 impacts). Then, the fracture morphology of all the specimens were characterized by the SEM. Finally, the strengthening mechanism was discussed based on the microstructural evolution and residual stress distribution. It was concluded that the enhancement of high cycle fatigue strength was attributed to the combined effects of LPwC-induced compressive residual stress and high-density dislocations.
Highlights
Titanium alloys, like Ti-6Al-4V and Ti-17, have the advantages of light weight, good toughness, high strength-to-weight ratio and excellent corrosion resistance, which makes it to be widely used in the aerospace and marine industries [1,2,3]
Based on the residual stress distribution, micro-hardness test and microstructural characterisations, it is likely that the improvements of the high cycle fatigue performance on Ti-17 titanium alloy after laser peening without coating (LPwC) are a consequence of the combined effects (1) according to the Goodman theory [43], the LPwCinduced high amplitude residual stress in the near-surface layer can reduce the effective working stress on the specimen, so the initiation of fatigue cracks in the surface layer is prevented
The effects of multiple laser peening without coating (LPwC) on the residual stress and micro-hardness distribution, microstructural evolution and high cycle fatigue strength of Ti-17 titanium alloy were investigated
Summary
Like Ti-6Al-4V and Ti-17, have the advantages of light weight, good toughness, high strength-to-weight ratio and excellent corrosion resistance, which makes it to be widely used in the aerospace and marine industries [1,2,3]. With these unique features, these alloys are widely used for the fabrication of the compressor and fan blisks that were called “cold” components in aeroengines [4]. Each one has its own advantages and drawbacks, for example, shot peening has low cost but may lead to the damage of the components surface, the major disadvantage of laser shock peening is that it requires an elaborated laser system with high power and needs to replace the protective coating after finishing one impact, which may affect the machining efficiency and costs
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 callMore From: The International Journal of Advanced Manufacturing Technology
Disclaimer: 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.
