[INVITED] A review: Warm laser shock peening and related laser processing technique

Warm laser shock peening without coating induced phase transformations and pinning effect on fatigue life of low-alloy steel

“…The thickness of BK7 glass confinement layer is 1 mm. In this case, WLSP parameters are being tuned to get a match of shock impedance between confinement glass layer and decarburized surface steel, in order to attain peak pressure (Table 1) [5,14,[18][19][20]51,52]. The laser power density used for the current experimental process is 5.97 GW cm −2 .…”

“…In order to avoid fast cooling of the pre-heated specimen during WLSP experiments, the electrical dryers are used for continuous heating of target specimen holder surroundings. Subsequently, the WLSP treated specimen are slowly cooled from the processing temperature to avoid RS relaxation [14,[18][19][20]51,52]. The authors earlier work investigated that direct laser ablation on the mirror polished surface works efficiently but, an anisotropic problem during the shock wave production is identified [5,21,24,27].…”

“…The optimum working temperature for dual phase spring steel was evaluated for shot peening process [16][17]. The thermal engineering based warm laser shock peening (WLSP) has advantages such as dynamic strain aging (DSA), and dynamic precipitation (DP) hardening of low-alloy steel which contributes an extensive improvement in fatigue life cycle [14,[18][19][20]51,52]. LSPwC method of producing high compressive RS works efficiently with low energy lasers.…”

Tensile Properties and Microstructures of a 2024-T351 Aluminum Alloy Subjected to Cryogenic Treatment

“…For example, in 2015, Liao et al [14] reviewed the processing techniques of warm laser shock peening (WLSP) and thermal engineered-laser shock peening (TE-LSP) systematically and explained the fundamental process mechanisms clearly. According to the review, a dislocation pinning effect based on the dynamic strain aging (DSA) and dynamic precipitation (DP) is the main reason for improvement of residual stress and microstructure stability of WLSP [14,15]. Chen et al [16] in Jiangsu University studied the effects of warm laser peening (WLP) on thermal stability of the A356 alloy and found that WLP can effectively improve the thermal stability of residual stress compared with LP.…”

Femtosecond laser peening of 2024 aluminum alloy without a sacrificial overlay under atmospheric conditions

“…7 In the case where a laser pulse with a near infrared wavelength ($1.05 lm) is used, the material's surface needs to be covered with a protective coating or a sacrificial layer such as a black paint or an aluminum tape to prevent the surface from melting or sustaining damage from the laser pulse. 4,8 After the laser treatment, the remaining coating needs to be removed. Laser peening without coating process was developed using 532 nm wavelength lasers by optimizing process conditions, which has been applied to practical uses in nuclear industries.…”