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Linear friction welding is a highly efficient solid-phase connection method, the overall leaf disc manufacturing and other fields have broad application prospects. Linear friction welding process is an accompanying efforts, the phenomenon of thermal and metallurgical complex process, the current experiments on linear friction welding has been a lot of research, but the linear friction welding process is very complex and a lot of hard physical phenomena and mechanisms through experimental means now Direct observation and analysis, many phenomena and mechanisms need from the microscopic point of view. Numerical simulation of linear friction welding current research is aimed mostly continuum, but many physical processes such as atomic diffusion is discrete. Therefore, from the atomic scale linear friction welding process analysis is necessary. In this paper, molecular dynamics method, from the atomic scale linear friction welding process is simulated, the establishment of linear friction welding Ni-Al molecular dynamics model, including friction phase and upsetting phase, the effects of different process parameters on the diffusion layer , the results showed that raising the top forging force and friction velocity to the total increase in the thickness of the diffusion layer has a role in promoting the friction velocity generated mainly on the friction phase diffusion layer has a greater impact, and upsetting phase diffusion layer generated mainly by Top forging force of impact. Based on this model, we studied the surface roughness of the linear friction welding process. The results show that the rough surface friction process gradually disappear, hard surface roughness when the welded interface tissue composition and structural implications, the rough surface of the softer material has little effect on the welded interface. By simulation, we have come when the surface roughness, the linear friction welding process is divided into three steps, the first and gradually close to each other on both sides of the contact material, the forging force and friction under the action of friction phase begins, soft material (Al) start to deform, so that both sides of the material has a larger contact area. Then, as the friction for a softer material (Al) increasing deformation, so that both sides of the interface material to achieve complete intimate contact. Finally, forging force is applied at both ends to complete the weld. In addition, we also studied the linear friction welding process to bridge the holes laws. Ni and Al both sides of the preset holes, in order to consider the diffusion layer at the interface of the holes, to consider holes near and far away from the interface of the case, the simulation results show that when the holes from the interface close, the holes in Bridging the welding process, Al-side holes in the friction phase bridge, Ni side holes in the top forging stage bridge; bridge the time when the holes are near the interface in the direction from the beginning to bridge. When the hole is farther away from the interface, Al-side holes in the bridge completely upset stage, while Ni side of the hole can not be bridged, and finally, the paper established a linear friction welding of finite element simulation model, a multi-scale simulation of linear friction welding ideas , the use of bridge-scale method of molecular dynamics simulation and finite element simulation combined for the future linear friction welding provides a complete numerical simulation methods.
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