Induction of through-thickness compressive residual stress fields in thin Al2024-T351 plates by laser shock processing

Abstract

Laser Shock Processing (LSP) has been demonstrated as an emerging technique for the induction of RS's fields in sub-surface layers of relatively thick specimens. However, the LSP treatment of relatively thin specimens brings, as an additional consequence, the possible bending in a process of laser shock forming. This effect poses a new class of problems regarding the attainment of specified RS's depth profiles in the mentioned type of sheets, and, what can be more critical, an overall deformation of the treated component.The analysis of the problem of LSP treatment for induction of tentatively throughthickness RS's fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration is envisaged in this paper.The coupled theoretical-experimental predictive approach developed by the authors has been applied to the specification of LSP treatments for achievement of RS's fields tentatively able to retard crack propagation on normalized specimens. A convergence between numerical code results and experimental results coming from direct RS's measurement is presented as a first step for the treatment of the normalized specimens under optimized conditions and verification of the crack retardation properties virtually induced.

On the prediction of fatigue crack growth based on weight functions in residual stress fields induced by laser shock peening and laser heating

“…6,8 In contrast to LH, the LSP process utilizes a pulsed laser that allows the generation of compressive residual stresses in the area where the LSP treatment is applied. 9,10 In case of the LSP process, material surface is usually covered with a flowing water layer. Having passed through the water layer, high-pulse energy (in the range of several J) in the focused laser beam (power density in the range of several GW/cm 2 ) is absorbed by the material surface, which turns into plasma.…”

“…The effect of the LSP treatment on the generation of compressive residual stresses under the surface is much deeper than that in case of traditional mechanical surface engineering techniques, such as sand blasting or shot peening. 5 Moreover, it is possible to generate compressive residual stresses, which can be even introduced through the thickness in case of thin sheet material without noticeable microstructural changes in the material, 10,11 which is not the case, for example, for shot peening. 12 Therefore, the application of LSP treatment can improve FCG resistance of structural components without any weakening of the material containing compressive residual stresses.…”

Experimental Determination of Electronic Density and Temperature in Water-Confined Plasmas Generated by Laser Shock Processing

“…Recently, works on the effect of the LSP process have also been presented by some of the authors of this study. A comparison between experimental values and numerical predictions of the inside propagation of the residual stresses in plates of Al2024-T351 of 2 mm thickness was presented in 2015 by Ocaña et al [10]. Also in 2015, a study on the influence of the randomness of the superposition of pulses on the final anisotropy of the residual stresses induced in the treated material was completed by Correa et al [11].…”

Utilización de la línea Hα del hidrógeno en la caracterización de los plasmas generados por láser para aplicaciones industriales (técnicas LSP) y espectroscópicas

“…Es el caso del campo de tensiones residuales inducidas en placas de Al2024-T351 de 2 mm de espesor, comprobadas experimentalmente por Ocaña et al (2015) o del análisis sobre la influencia de la aleatoriedad de la superposición de pulsos sobre la anisotropía final de las tensiones residuales inducidas en el material tratado, publicado por .…”

“…Recently papers on the effect of the LSP process have been presented by some of the authors of this paper. As an example: Residual stresses through the thickness of 2 mm thick Al2024-T351 plates are demonstrated experimentally by Ocaña et al (2015)., also in 2015 a study on the influence of the randomness of the superposition of pulses on the final anisotropy of the residual stresses induced in the treated material were analyzed by Correa et al (2015).…”