Laser Peening Without Coating: Process, Effects And Applications

Author:  Y. Sano, N. Mukai, M. Obata
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008104
Year of Publication:  2008
ABSTRACT This paper reviews the current status of research, development and application on laser peening without coating (LPwC). LPwC imparts compressive residual stress on material by irradiating laser pulses under aqueous environment without any surface preparation. LPwC can be operated without restriction on absorption by water, using water-penetrable green lasers. The effect penetrates 1mm or more, much deeper than that of conventional surface treatment such as shot peening. Accelerating stress corrosion cracking (SCC) tests showed that LPwC effectively prevented the initiation of SCC in sensitized austenitic stainless steels, nickel-based alloys and their weld metals. LPwC remarkably improved high-cycle fatigue properties of steels, aluminum alloys, titanium alloys. Retardation of crack propagation due to stress corrosion and fatigue was also confirmed. LPwC has been utilized to prevent SCC in Japanese nuclear power plants (NPPs) since 1999. KEY WORDS Laser peening, Residual stress, Stress corrosion cracking, Fatigue

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