7049 AL-Alloy Fatigue Behavior under Black Paint Laser Peening

Abstract

Black Paint Laser (bPL) peening technique is currently applied to engineering components due to their improvements of fatigue behavior and economic advantages. In the current work, the experimental examinations of bPL peening, which aims to understanding the fatigue behavior of bPL surface treated bars was carried out. The application of bPL was associated with significant extension of fatigue life and strength. This extension is due to compressive residual stresses (CRS) generating from peening process. A series of fully rotating bending fatigue tests was conducted at room temperature using 7049 Aluminum alloy. Improvements in fatigue life and strength for constant and cumulative fatigue were demonstrated. Finally, the fatigue strength of 7049 Aluminum alloy at 107 cycles increased by 53% and cumulative fatigue life improved by factors of 1.55 and 1.787 for Low-high sequence and high-low sequence due to bPL treatment respectively.