Fatigue properties of high strength steel treated by laser peening with handheld microchip lasers

Author:  Y. Mizuta1, S. Tamaki2, T. Kato3, Y. Sakino3, T. Hosokai1 and Y. Sano1 1 SANKEN, Osaka University, Ibaraki, Japan 2 LAcubed Co. Ltd., Yokohama, Japan 3 Kindai University, Higashi-Hirochima, Japan 4 Institute for Molecular Science, National Institutes of N
Source:  ICSP14 Milan
Doc ID:  2022072
Year of Publication:  2022
Abstract:  
Abstract Laser peening (LP) introduces compressive residual stresses (RSs) on the surface of metallic components covered with water by irradiating them with high intensity laser pulses [1-7]. The advantage of LP is the possibility of fine execution management and the capability to introduce deep compressive RS on the material surfaces. It is well known to be highly effective in inhibiting stress corrosion cracking and fatigue cracking on material surfaces [7]. In addition, LP has an excellent effect on improving the fatigue strength of welds, which compensates for the disadvantage of high strength steels when welded. LP has a high potential for enhancing material surface, but the high-power laser used requires clean room facilities, large equipment and severe operating conditions. Therefore, the application of the LP has been limited to the countermeasure against high cycle fatigue of jet engine fan blades and stress corrosion cracking of nuclear reactor structures. If microchip lasers, which are small and easy to handle, could be used as a light source for LP, it would be possible to apply them not only to production processes in factories but also to existing steel structures such as bridges, to which conventional lasers have been difficult to apply for the above reasons. Based on this idea, we have developed a compact mobile LP device and verified its performance. [8-9] Keywords Laser peening, microchip laser, handheld laser, residual stress, fatigue