Research on Laser Welding Process and Deformation Control of Irradiated Sample Holder

Abstract

In order to study the influence of laser welding parameters on the weld formation and the deformation of the irradiated sample holder, laser lap welding tests were carried out on 304 stainless steel sheets with the thicknesses of 8.97mm and 20mm. Firstly, orthogonal tests were carried out to study the effect of welding speed and defocus on weld morphologies. The results showed that when the laser power was 10kW, the welding speed was 15mm/min, and the defocus amount was −1mm, the optimized weld with the aspect ratio of 2.13 can be obtained. Next, a novel fixture designed for the welding of the irradiated sample holder was introduced, which effectively reduced the deformation of workpieces during the welding process. Additionally, in order to compensate the deformation induced by the weld shrinkage and residual stress, a filler gauge of 0.75mm height was used to create an inverse deformation. it was proved that the welding deformation could be effectively controlled after the preforming, and the deformation could be controlled below 0.7mm. Finally, the influence of welding sequence on the deformation of the irradiated sample holder under the optimized welding parameters was investigated. It was shown that the optimal welding sequence of the irradiated sample holder was: firstly the arc positioning welding, then the laser positioning welding, and finally the laser deep penetration welding. The welding deformation can be effectively controlled by adding the fixture and adjusting the welding sequence, the change of flatness before and after the laser deep penetration welding could reach 1.09mm.