Optimization of laser repair parameters for precracked 304 stainless steel components with nanocomposites addition

The optimization of process parameters is usually essential for achieving improved properties at efficient and cost-effective process conditions. The influence of laser parameters, i.e. laser power, spot diameter, and laser heating time, on the fracture property of repaired specimens was investigated by Taguchi experiment. Cracks were first fabricated on 304 stainless steel compact tension specimens by wire cutting and then repaired by adding nanocomposites at crack tips under different combinations of laser parameters. The repairing effects were evaluated by crack opening displacement measured by digital image correlation and microstructure characterized by scanning electron microscope. The analysis of variance was used to investigate the contribution of factor variables to the fracture parameter of crack opening displacements. The fracture property was improved most at the optimal repair process parameters of laser power of 1800 W, spot diameter of 3 mm, and heating time of 0.5 s within the selected range of experiments. The influence of laser parameters on the fracture properties of repaired specimens is found in the sequence of spot diameter, laser power, and heating time. This paper reveals the relationship of process–microstructure–fracture property in laser repair and provides a guideline for the selection of laser parameters to improve the quality of crack repair.