On August 20, 2021, Aachen, Germany, a team from the Fraunhofer Institute for Production Technology (IPT) introduced an additive manufacturing (AM) process that combines wire-based and powder-based laser melting cover. According to the team, the protective tool coating produced by this hybrid process is more wear-resistant, more resource-efficient and more cost-effective than coatings produced by traditional laser cladding methods. The hybrid process is also more flexible than pure wire-based coating methods.
Laser cladding produces a 3D structure through laser metal deposition (LMD); in the LMD process, the surface of the workpiece is heated with a laser beam, and at the same time, the filler material in the form of powder or wire is fed into the molten pool area. When the filler melts, it forms a coating on the surface. The structure can be built layer by layer directly on the surface of the workpiece. LMD is an effective method for applying protective coatings, repairing damaged components, or changing the geometry of the workpiece.
In the IPT hybrid method, wire and powder materials are processed simultaneously during LMD. Scientists have discovered that by adding hard material particles in powder form to the wire, they can use LMD for the first time to adjust important material properties in the coating, such as hardness and toughness.
In order to determine the best combination of materials for different applications, the scientists tested various materials. For the wire, they chose hot work tool steel with high structural stability and low alloy steel with good weldability. For powder materials, they chose chromium as the carbide formation and grain refinement element, and titanium carbide (TiC) as the hard phase.
Through the combination of powder and wire, scientists can customize the composition of the material for each application. They selectively changed the microstructure of the tool steel and added powder to increase the hardness of the coating. Even if a small amount of TiC is added, the hardness will increase by 30%.
The tool coating produced by a hybrid AM process developed by a team of Fraunhofer IPT is more wear-resistant, more resource-efficient and more cost-effective than other tool coatings, provided by Fraunhofer IPT
“With the new process, we can now respond quickly and flexibly to different thermal, chemical and mechanical loads because we can precisely adjust toughness and hardness,” said project manager Marius Giperich.
According to Giperich, the new mixing process is ideal for minimizing surface wear and extending the life of components. It is more cost-effective than the pure powder process and has greater material flexibility than the pure wire process.
The scientists plan to apply their method to the development of other material systems with special properties. They also plan to use the hybrid process for the processing of forming tools and the treatment of friction and wear layers of hydraulic components.
Currently, the IPT team is testing the use of hybrid processes in the production of hierarchical coating systems. As part of the test, the team plans to increase the TiC content of the material mixture as much as possible. Because TiC can cause high residual stresses, thereby increasing crack susceptibility during welding, the team plans to adjust the TiC content layer by layer.
Link to this article： Wire and laser cladding “enabling” coating
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