Thermo-mechanical model for simulating laser cladding induced residual stresses with single and multiple clad beads

A three dimensional finite element (FE) model was developed to simulate residual stress induced for laser cladding of AISI 4340 steel powder onto a similar substrate material. A laser power attenuation model was proposed for the laser-powder-interaction zone under the coaxial powder feeding nozzle. The thermal analysis integrated the deposition of clad beads with laser heating. This was performed using user-defined subroutines to thermally activate clad element conductivity and surface heat transfer film conditions simultaneously with the translating attenuated laser heat flux. The FE model investigated three case studies: (i) laser heating without powder feeding, (ii) deposition of single clad bead and (iii) deposition of double adjacent clad beads. The numerical results of the thermal field were compared with thermocouple measurements and heat affected zone (HAZ) sizes from experimental specimens cross-sectioning. X-ray diffraction (XRD) stress measurements were performed to validate the modeled residual stress in case (ii). The FE model was subsequently applied to simulate cladding 10 clad beads over an area to study the effects of depositing multiple successive clad beads on residual stress field.