INVESTIGATION OF THE SURFACE QUALITIES OF LASER SHOCK-PROCESSED ZONESAND THE EFFECT ON FATIGUE LIFE OF ALUMINUM-ALLOY

The influence of surface qualities produced by laser shock-processing (LSP) on the fatigue life of aluminum alloy 2024T62 are investigated. The surface qualities of LSP zones can be divided into grades A, B, C and D. The harmful heat damage produced by LSP is completely avoided i n grade A surface quality, but heat damage exists to some extent in th e others. Therefore, the grade A surface quality reflects the LSP cont ribution to fatigue life, which increases greatly. The main feature of grade A surface quality is that the surface roughness of the LSP zone is less than or equal to the surface roughness of the un-shocked zone . A very dense bright shallow hollow is formed and the shot spot is we ll-defined. With 95% confidence, the mean fatigue life of LSP specimen s with grade A surface qualities is 4.8-8.1 times larger than the un-s hocked ones.