Residual Stress Stability at Elevated Temperatures
Several components used with laser peening operate in service conditions with elevated temperature exposure. As temperatures near upper limits of material usability there is the potential for thermal stability of the residual stresses. To retain the benefits of the residual stresses at higher service temperatures, the residual stresses must be resistant to thermal recovery. A titanium alloy, Ti-8Al-1V-1Mo , was laser peened, then held at elevated temperatures in the service temperature range of interest, for four hours. After these anneals, the residual stress profiles were measured and compared to the non-annealed specimens. The results, presented in Figure 1, show that after four hours at elevated temperatures there is no loss of residual stress and the residual stresses induced by laser peening are thermally stable.
Figure 1 - In-depth residual stress profiles after annealing Ti-8Al-1V-1Mo for 4 hours at elevated temperatures.
1. C. Lykins, P. Prevey, and P. Mason, Laser Shock Peened Compressive Residual Profile After Exposure to Temperature, AF Report WL-TR-95-2108, September, 1995, Wright Patterson AFB, OH.