TABLE OF CONTENTS The development of LSP processes has been comprehensively reviewed and addressed in this chapter. LSP has an impressive capability to improve the mechanical performance of metallic materials. The advantages and disadvantages as well as some challenges in applications of LSP can be summarised as follows.
For potential industrial applications, laser sources for LSP require much better output performance, such as output power and repetition rate in the near future. Selection of a laser source for LSP is also required to consider two aspects: (1) the laser wavelength must be convenient in a water-confined environment; (2) the laser equipment has to be small enough to handle and easy enough to operate in situ in the working field.
A high shock pressure can be generated by means of a transparent overlay and absorbent coating on a metallic material during an LSP process. Absorbent coatings can be metallic, organic paints or adhesives. The coating not only protects the metal surface from melting but also increases the magnitude of the shock pressure. The uncoated material surface can lead to very high tensile stresses, even with transparent overlay, attributed to severe surface melting. Transparent overlays can be water or glass, confining the laser energy. In order to achieve the best treatment results for individual metallic materials, the optimisation of LSP parameters, such as laser parameters, transparent overlay and absorbent coating, is very important for effective treatment.
Peak pressure as high as 5.5 GPa with pulse duration of about 55 ns in the...
