Originally published by Lasers In Materials Processing, 1983, pp. 7-22.
Authored by Allan H. Clauer, Craig T. Walters, and Steve C. Ford.
The effects of laser peening have been investigated in a number of metals and alloys with increases in hardness and tensile and fatigue strengths reported (1-7). A previous study of the fatigue response of laser shocked aluminum alloy plate containing simulated fastener holes showed marked increases in fatigue life in some cases. In addition, the study suggested certain process and geometry changes which would either further enhance the fatigue property improvements or aid in understanding and controlling the laser shock phenomenon influencing the properties (7). This paper describes the effects on fatigue life resulting from several different laser beam geometries and process conditions.
Both solid beam and annular beam geometries were used. The annular beam was added to determine whether a crack could be slowed down by encountering a laser shocked region. In addition, specimens were shocked from both sides simultaneously, from both sides consecutively with a momentum trap on the unirradiated side, and from one side only with a free surface opposite the irradiated side. The purpose of the momentum trap was to minimize the effect of the reflected wave from the surface opposite the irradiated surface. The one-side only shot without the momentum trap was to enable comparison to be made between the full effect of the tensile stress wave reflected from the surface opposite the irradiated side to the effects of a once through passage of the shock wave, i.e., with the momentum trap.
To understand the observed effects on the fatigue life, surface and in-depth residual stress distributions were determined for each of the laser beam geometries and process conditions. Both the residual stress and fatigue results are presented and discussed.
To download the entire article- as a pdf: The Effects of Laser Shock Processing on the Fatigue Properties of 2024-T3 Aluminum