Contrastive analysis of temperature and stress field distribution in cladding layer by the Gaussian and hollow-ring laser modes.

The Gaussian laser mode can be converted into a hollow-ring laser mode through beam conversion system, realizing the conversion of circular and solid spot into a hollow-ring spot, which changes the energy distribution form of the laser spot. In order to study the effects of the Gaussian and hollow-ring laser modes on temperature and stress fields in cladding layers, the numerical simulation and experimental investigation were performed. The results showed that molten pool experienced once temperature peak and generated sharp temperature change under the Gaussian laser, while the molten pool experienced twice temperature peaks and temperature changed relatively gentle when using hollow-ring laser. Comparing with the Gaussian laser, the maximum temperature gradient along the depth of cladding layer decreased by 72.3% from 1.79 × 106 to 4.95 × 105 ℃/m, and the maximum residual stress decreased from 272 to 251 MPa under hollow-ring laser. Meanwhile, the simulation results were validated by experiments with the same process. Furthermore, the sample microstructure was studied from the experiment. The microstructure was finer and more uniform using hollow-ring laser. This paper can provide guidance and advantage for laser cladding and direct metal deposition based on the hollow-ring mode and expand the application of laser field. [ABSTRACT FROM AUTHOR]