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Contemporary Machining Processes for New Materials
Published in E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan, Remanufacturing and Advanced Machining Processes for New Materials and Components, 2022
E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan
Laser is also used for supporting other surface engineering techniques, for example, enhanced electroplating. In this method, irradiation of a laser beam on a substrate (cathode) during electrolysis promotes drastic modification of the electrodeposition process in the irradiated region. Other applications of lasers to surface engineering are laser cleaning, paint stripping or laser surface roughening. The latter, executed with pulses from an excimer laser, improves adhesion of glue to a surface. Laser shock hardening or “laser shot peening” has emerged as an industrial process able to create a compressive stress in a surface and thus increase fatigue strength of a component's material (Steen, 2003).
Assessing the dynamic characteristics of a femtosecond laser micro plasma expansion process with an optical fiber sensing probe
Published in Khaled Habib, Elfed Lewis, Frontier Research and Innovation in Optoelectronics Technology and Industry, 2018
The diversity of phenomena that arise during the development of the interaction between lasers and materials inducing plasma has promoted research within this discipline in recent years (Eliezer, 2002). A significant amount of laser plasma research has involved the characterization of the transient response of laser-generated plasma, primarily associated with the ablation of target materials using short-pulse, high peak-power lasers (Bulgakova et al., 2000; Kabashin et al., 1998). Laser plasma research has found a wide range of applications. The study of laser plasma dynamic characteristics provides a new development direction for laser shock strengthening processing, laser shock forming, laser cleaning, laser-induced fusion, laser propulsion, laser medicine and other fields. At present, a series of researches have been carried out, both at home and abroad, into the dynamic characteristics of the laser plasma expansion process. These researches have especially made great achievements in the theoretical study of the dynamic characteristics of nanosecond-pulsed laser plasma expansion. The simulations by the existing nanosecond or longer-pulse laser ablation target material are mostly based on the classical theory of heat transfer. The establishing of a dynamic model of laser ablation plasma plume steady expansion was mainly through the related research into the transmission of pulse laser (Bogaerts et al., 2011). On the femtosecond scale, nanosecond and long-pulse laser ablation model is no longer applicable (Lv et al., 2009). In order to obtain the dynamic characteristics of the plasma expansion process induced by femtosecond laser ablation target material, laser-induced plasma diagnostic techniques are used in experimental research. Garnov et al. used over-speed spectroscopy to observe the process of plasma formation, progress and ionization at the early stage (Garnov et al., 2009). Liu et al. researched the influence of liquid environments on the femtosecond laser ablation of silicon (Liu et al., 2010). Gao et al. studied the plasma space and time-resolved emission spectra by the femtosecond-pulse laser ablation silicon (111). Gao et al. summarized the evolution of plasma plume expansion space emission wavelength shift and spectral intensity process (Gao et al., 2011). Odachi et al. studied the work on the ablation of crystalline silicon by femtosecond laser pulses in air and vacuum (Odachi et al., 2013). However, these techniques are mainly concerned on molecular spectroscopy. They cannot comprehensively monitor the dynamic characteristics of the plasma expansion process.
A metal marking method based on laser shock processing
Published in Materials and Manufacturing Processes, 2019
Guoxin Lu, Jing Li, Yongkang Zhang, David W. Sokol
Laser shock treatment can lead to severe plastic deformation on the surface of the material. Severe plastic deformation contributes to the main strengthening effect (e.g., by introducing a residual compressive stress field or/and inducing microstructure evolution, etc.), and directly causes the surface of the material to form a distinct concave shape[8]. Prior to laser shock treatment, the surface of the material to be treated should be coated with an absorbing (coating) layer. The purpose of the coating treatment is to[9]: (i) increase the absorption capacity of the laser radiation, (ii) increase the pressure wave peak, and (iii) prevent the metal surface from melting and gasifying[10]. Many materials can be used as the absorbing (coating) layer, such as graphite, black lacquer, zinc, etc. Currently, aluminum foil or black tape is the most commonly used absorbing (coating) layer material[11].
Microstructure-crystallographic texture and substructure evolution in unpeened and laser shock peened HSLA steel upon ratcheting deformation
Published in Philosophical Magazine, 2023
Pushpendra Kumar Dwivedi, R. Vinjamuri, Krishna Dutta
When subjected to ratcheting deformation, the unpeened specimen undergoes a drastic transformation from {011} < 211 > to rotated Cube {001} < 110 > texture component. On the other hand, the laser-peened specimen's {011} < 111 > texture component completely disappears and is replaced by a weak rotated Goss {011} < 011 > texture component. This formation of the rotated cube texture component is related to the occurrence of dynamic recrystallisation during the ratcheting process for the unpeened specimen [61–64]. However, for laser-peened specimens, the change in texture to the rotated Goss component makes it less susceptible to ratcheting failure. The texture intensity of the unpeened specimen slightly increases from 3.364 to 3.655 m.r.d. after ratcheting, while the laser-peened specimen's texture intensity drastically drops from 4.265 to 2.744 m.r.d. This decrease in texture intensity means that there is less texture-induced anisotropy in the material, leading to improved fatigue performance. Additionally, the residual compressive stress created by the laser shock peening process can also help to improve the material's fatigue resistance by reducing the amplitude of the cyclic stress experienced by the material. These ODF sections contained numerous more diffuse texture components in addition to the θ-fibre, γ-fibre, and α-fibre texture components. This implies the presence of both the original and the recrystallised textures. After deformation, the overall texture strength was increased in the unpeened condition and decreased in the laser-peened condition, with the greatest orientation density in the recrystallised specimens being more than that of the original material.