Hybrid welding methods for advanced materials

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The latest advances in laser welding technology have brought new capabilities to control the delivery of heat and filler material to the pieces being joined. New technologies such as high frequency scanning, and combining laser with arc welding torches in hybrid-laser welding have enabled more flexibility in joining a broader range of materials. The total power and energy density of modern fiber lasers also enables high joining speeds to be achieved without excessive heating the surrounding materials, and this is vital to successful joining of modern high strength materials, and dissimilar combinations of metals.    This proposal will develop processing conditions and filler materials using a state-of-the-art hybrid-laser welding system that has been custom designed to combine the latest technologies. The system is unique in North America and incorporates an 8kW fiber laser coupled with an arc welding torch and two supplementary wire feeders which enable a vast range of weld metal chemistries to be deposited during welding. The shape of the molten weld pool will be controlled by high frequency scanning optics which can focus a 0.2 mm spot size to the location where heat is required. This level of control will provide a flexibility to join new material combinations such as aluminum to steel for light weight vehicles, and zirconium to steel for power generation equipment. Also, new ultra-high strength alloys will be developed by continuously adjusting the rate of multiple different metal wires fed into the weld pool, and evaluating the deposited material properties along the length of the one joint with varying chemistry. This will realize a `rapid prototyping of materials' concept, which can be used to quickly develop new filler metals for joining applications in the future.    The research will also generate a new understanding of how to effectively apply hybrid-laser welding parameters to join the most difficult combinations of materials. The properties of the joints and weld metals will be tested using the most sophisticated mapping techniques that can determine the yield stress and hardness of material at microscopic scales, providing detailed information for specifications that can be used for design in industry. The students involved will not only become experts in applying new manufacturing processes, but also gain leading-edge skills in new testing methods and characterization using electron microscopy, allowing them to later advance the practices in industry when they graduate.