Effect of Laser Parameters on Microstructure and Fracture Properties of Repaired Cracks with Micro/Nano Material Addition

Abstract

Compact tension specimens with prefabricated cracks are repaired by laser with micro/nano materials added at the crack tip. Different combinations of laser parameters, i.e., laser power, laser spot diameter and heating time, were applied to investigate their effects on the microstructures and fracture properties of repaired specimens. J-integrals were calculated according to the digital image correlation (DIC) measurements, and microstructures were examined using scanning electron microscopy (SEM). When suitable laser parameters were used, homogeneous and compact equiaxed grains with no cracks, pores, and agglomeration are observed in the repaired layer, and the J-integral of repaired specimens is approximately 20% less than that of unrepaired specimen. The paper reveals relations among laser parameters, J-integrals, and microstructures, and provides a guideline for the selection of laser repair parameters.