Warm-laser shock-peening was a new high strain rate surface strengthening process that was demonstrated to significantly improve the fatigue performance of metallic components. This improvement was mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which were generated by dynamic precipitation during the warm-laser shock-peening process. Here, the dislocation pinning effects induced by the nanoscale precipitates during warm-laser shock-peening were systematically studied. Aluminum alloy 6061 and AISI4140 steel were selected as the materials with which to conduct warm-laser shock-peening experiments. Multiscale discrete dislocation dynamics simulation was conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation was studied. The dislocation structures after warm-laser shock-peening were characterized via transmission electron microscopy and were compared with the results of the multiscale discrete dislocation dynamics simulation. The results showed that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect was strongly affected by the density, size, and space distribution of nano-precipitates.

Dislocation Pinning Effects Induced by Nano-Precipitates During Warm Laser Shock Peening: Dislocation Dynamic Simulation and Experiments. Y.Liao, C.Ye, H.Gao, B.J.Kim, S.Suslov, E.A.Stach, G.J.Cheng: Journal of Applied Physics, 2011, 110[2], 023518