Study on a multifield coupling mechanism and a numerical simulation method of a pulsed laser deposition process from a disk laser

Abstract

Pulsed laser deposition produces heat in an alternating fashion, which allows for more cooling time and accumulates significantly less heat than continuous laser deposition. This is conducive to heat dissipation, leading to the formation of a larger temperature gradient in the cladding layer, a fine-grained structure and good mechanical properties. There are extremely complex heat transfer and thermal-elastic–plastic-flow coupling changes that occur during a pulsed laser deposition process from a disk laser. Quantitatively revealing the multifield coupling mechanism in a pulsed laser deposition process is a key to process optimization. In this paper, a numerical model of pulsed laser deposition from a disk laser was established for cladding Fe60 powder on an ASTM 1045 matrix. In the model, the interactions between the powder flow and the pulse laser beam and the influence of surface tension and buoyancy on the Marangoni fluid flow in the molten pool were considered. The model was solved, and the distribution states and evolution laws were obtained for the temperature, velocity, and stress fields in the pulsed laser deposition process. On this basis, a comparative analysis of pulsed laser cladding and continuous laser cladding was carried out from the perspective of numerical simulations and experiments, revealing the influence of pulse parameters on the multiphysics of laser cladding. The microstructure of the pulsed cladding specimen was analyzed by a Zeiss-ƩIGMA HD field emission-scanning electron microscope. The experimental results were in good agreement with the calculated results, and the accuracy of the model was verified.