Investigation Of Laser High-Speed Impact Synchronous Welding And Forming

Based on the laser-driven flyer micro forming and laser high-speed impact welding, this paper puts forward the laser high-speed impact synchronous welding and forming new process, and build the compound welding experiment platform which combines the characteristics of laser indirect shock microforming and laser high-speed impact welding. The main research work and achievements are as follows:Firstly, the force effects model of the interaction between the laser and the material was studied, and the mathematical model of the shock wave pressure was derived. The interface formation, the morphology and the wave formation mechanism of the welding interface were analyzed based on the relevant theory of the high-speed impact welding.Secondly, the combination of Al/Al was studied by the laser high-speed impact synchronous welding and forming experiment. The three-dimensional deep field digital microscope of KEYENCE VHX 1000 C was used to measure the surface morphology and fittability of the welding and forming sample. From the observation of the sample surface morphology, strong plastic deformation occurs on the surface of the material to reproduce the shape of the mold. The fittability of the sample increased with the increase of the laser energy when the laser energy was relatively small. However, the fittability decreased because the rebound phenomenon occurred at the bottom of the welding and forming specimen when the laser energy is larger than 4.5J. The Axio CSM 700 confocal microscope was used to measure the sample surface roughness and the morphology of the welding interface. Results showed that the surface roughness increased with the increase of the laser energy and the standoff distance. The cross profile of the welding interface showed that most areas of the welding interface has been welded. The nano indentation instrument was used to measure the hardness near the welding interface. Results showed that the hardness of welding interface area has a certain degree of improvement, and the increase of microhardness of the material was more obvious when it was closer to the welding interface.Then the dissimilar metal materials Cu/Al was further explored in the experiment. The KEYENCE VHX-1000 C was used to measure the fittability and surface roughness of the samples. It was found that the fittability increased with the increase of the laser energy and the surface roughness increased with the increasing of the laser energy and the standoff distance. The Axio CSM 700 was used to observe the morphology of the welding interface. Research indicated that there were periodic sine wave and straight wave on both sides of the welding interface, but the bottom of the welding interface was not welded. The nano indentation instrument was used to measure the hardness near the welding interface. Results showed that the increase of microhardness of the material is more obvious when it was closer to the Cu/Al welding interface. The X-ray energy dispersive spectrometer was used to analyze the elements of the welding interface. The welding interface elements have a certain degree of diffusion and the diffusion layer width was about 1.5 microns.Finally, the smooth particle hydrodynamics method was used to simulate the laser high-speed impact synchronous welding and forming process and well simulate the phenomenon of jet and the welding interface temperature. The study showed that the welding interface temperature did not exceed the melting point of materials, and the materials did not melt. The opposite shear stress direction in the flyer and base plate and effective plastic deformation exceeded a certain threshold and can form effective solid metallurgical combination. The effective plastic deformation of the materials increased as the impact velocity increase. The welding interface morphology turned from straight to microwave, and finally large corrugated appeared. The collision angle between the flyer and base plate and the welding area increased gradually as the standoff distance increased. The interface wave form transfered from straight to wavy, and even emerged the vortex wave.As a novel welding and forming technology, laser high-speed impact synchronous welding and forming technology has high research value and good application prospect. The present work can lay technology foundation for engineering application of similar and dissimilar metal materials.