Yangtze River Delta G60 laser alliance guide
突尼斯苏塞大学及斯法克斯大学的科研人员综述了激光强化：因素、影响、应用、与喷丸强化的比较以及最新技术。 相关论文以“Laser Peening: A Review of the Factors, Effects, Applications, Comparison with Shot Peening and State-of-the-Art”为题发表在《Metals and Materials International》上。
Lasers can be used in a variety of traditional mechanical applications such as cutting, welding, surface treatment, etc. Laser Impact Enhancement (LSP) is an innovative surface treatment method that uses the mechanical effects of pulsed laser radiation. As a result, it produces deep work hardening and plastic deformation. This process is used in different mechanical fields such as defense, automotive, MEMS, mechanical engineering, and especially in aviation. This review presents an overview of LSP processing and some of its applications. The various factors of the process are also described. In addition, the effects of laser impact strengthening on the mechanical and metallurgical properties, surface roughness, damage, and fatigue resistance of treated parts are discussed. A comparison was also made between the laser impact strengthening process and the shot peening strengthening process. Various existing analyses and numerical models that predict induced effects were also analyzed and compared. In addition, the challenges and limitations of LSP processing were highlighted.
Yangtze River Delta Laser Alliance Chen Changjun
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In the field of surface improvement technology of metal alloys, laser impact strengthening (LSP) and shot peening strengthening (CSP) have attracted much attention because of their beneficial residual stresses. While LSPs and CSPs employ different mechanisms and approaches, they share the same goal of improving material properties. CSP involves high-speed strengthening of the surface of a material using spherical particles, such as steel shots or ceramic balls, to induce plastic deformation and generate residual stresses.
Figure 1: LSP process principle.
Figure 2: Direct and closed ablation (schematic).
Figure 3: Factors influencing LSP processing results.
On the other hand, LSP is an important surface strengthening technology with some unique advantages and applications. By inducing residual stresses, LSP can significantly improve the mechanical properties of metal alloys. LSPs are the first choice for reinforcing critical components in a wide range of industries due to their ability to enhance fatigue resistance, increase hardness, and reduce stress corrosion cracking. In addition, the local-accurate physical properties of the LSP allow for centralized processing, minimizing the risk of localized area deformation or damage. This non-chemical, non-contact process revolutionizes materials engineering, opening up new avenues for enhancing structural integrity, extending component life, and improving overall performance. Thanks to its proven technology and continuous research, LSPs are powerful tools for optimizing materials and promoting innovation in different fields such as aerospace, automotive, and biomedical applications. In fact, LSP treatment can create a layer of residual stress on the surface that is four times deeper than shot peening (CSP).
Figure 4: Surface roughness after laser impact: a square impact, b circular impact.
Figure 5: Mechanism of LSP process deformation and residual stress.
This review paper highlights the principles of the LSP process. Compared to previous reviews, this article provides a more in-depth analysis of the factors affecting the LSP process, such as: initial confined or transparent layer, opaque or ablative layer, applied pressure, laser spot size, structure of laser impact, laser pulse duration, and overlap rate. In addition, the researchers have studied in detail the different effects on various properties such as residual stress, microstructure, hardening, roughness, damage, fatigue life, friction fatigue and stress corrosion cracking. In addition, the researchers highlighted the industrial applications of LSPs, especially in the aerospace sector.
Figure 6: TEM micrograph of mild steel treated with LSP process, showing dense dislocation structure.
Figure 7: SEM micrograph of the effect of LSP treatment on the microstructure of 6061 aluminum. a. The microstructure before LSP treatment shows some dislocations. b. The microstructure after LSP treatment shows an increase in dislocation density.
In this review paper, laser impact strengthening (LSP) is a highly effective surface treatment technique that can significantly improve the fatigue life and damage resistance of metal components. Compared to traditional shot peening (CSP), LSP has the advantage of creating deep residual stresses with minimal material removal rates, which in turn improves the mechanical properties of the material.
Figure 8: LSP treatment of a turbine blade. b Turbine blades.
Figure 9: A LSP-treated T-45 stop hook. b LSP-treated leaves.
Figure 10: Stress corrosion enhancement.
Figure 11: Unprotected Coating Laser Shock (LPwC) to delay the application of SCC.
In conclusion, further research and development is needed to fully understand the complexity of the LSP process and its potential applications in various industrial sectors. This includes studying the effects of LSP on other mechanical properties such as fatigue crack growth, wear and corrosion resistance, as well as optimizing process parameters for different materials and component structures. In addition, further research is needed on the potential of LSPs as viable alternatives to CSPs in a variety of applications.
Paper Links:
AYEB, M., FRIJA, M. & FATHALLAH, R. Laser Peening: A Review of the Factors, Effects, Applications, Comparison with Shot Peening and State-of-the-Art. Met. Mater. Int. 30, 259–283 (2024). https://doi.org/10.1007/s12540-023-01517-4
Reprinted by Chen Changjun of the Yangtze River Delta G60 Laser Alliance