Effects of laser shock processing on microstructure and mechanical properties of K403 nickel-alloy

Owing to the cracks, fracture problem of nickel-based alloy K403 casting components, the effect of multiple impacts on the mechanical properties and microstructure of the K403 nickel alloy subjected to laser shock processing were investigated. Microhardness, residual stress and fatigue life were tested on samples to analyze the mechanical properties, and X-ray diffraction and transmission, electron microscopy (TEM) analyses were used to investigate the microstructure evolution. Microhardness and residual stress of the K403 nickel alloy were improved, by forming a plastic deformation layers. Additionally, increasing the numbers of impacts improved the hardness and residual effect depth. Similarly, the fatigue lives of samples subjected to 3 impacts increased by 244%. Meanwhile, TEM analysis indicated that a randomly-oriented nanoaystal formed after 3 impacts. In addition, the research on the mechanism of grain refinement of the K403 nickel alloy is discussed. (C) 2015 Elsevier Ltd. All rights reserved.