Simulation of temperature field and residual stress in high-power laser self-melting welding process of CLF-1 steel medium-thick plate

Abstract

To mitigate the adverse effects of residual stress and deformation during high-power laser welding, this study established a finite element model based on thermodynamic conditions for high-power laser welding of CLF-1 steel for nuclear fusion applications. The temperature field and residual stress of the weld were simulated by using the composite heat source model together with Gaussian model and conical model. The results showed that the temperature field simulation was in good agreement with the real temperature field. The simulation results of the weld metal (WM) and the heat affected zone (HAZ) in the cross sections were basically consistent with those of the real cross sections. Moreover, the margin of error between the simulation results and the real data was ≤ 1.3% (the largest error ≤0.04 mm). The Von Mises equivalent stress in WM was distributed irregularly, and its largest value was ≤ 220 MPa; the equivalent stress declined with an increase in distance from the center of WM. The transverse stress distribution in the center of WM was in accordance with the vertical stress distribution, which was essentially the same as the experimental data of the vertical stress. The simulation results of deformation in the Z direction of the weld showed that the maximum deformation was about -0.2 mm at the center of the weld corresponding to the length of 300 mm. In summary, the thermal source model, combined with laser welding process parameters, can provide high-precision prediction of stress variations and deformation control during the actual welding manufacturing process of the test blanket module (TBM) structure.