High Technology Research and Development Program of China (No. 2014AA041701), the National Natural Science Foundation of China (Nos. 51171179, 51271174, 51331005, 51501219, and 11332010) and the Natural Science Foundation of Liaoning Province in China (No. 2015020115).
Surface topography of an upsetting wrought superalloy processed by laser shock peening was observed in microscale and a series of morphological characteristics such as surface reliefs with special orientation, destructive dimples were found. The longitudinal sizes of the micro surface structures are within 100 nm to 1000 nm generally. The mechanical response laws of metal materials under laser shock were proposed to explain the emergence of the special micro-structure characteristics. It can be concluded that the formation of surface reliefs is a release way of the internal stresses under laser shock and small dimples are deemed as an external representation of the release of impact energy in the mode of fracture damage.