Improving the Mechanical Properties of Laser Beam Welded Hybrid Workpieces by Deformation Processing

Today's competitive manufacturing world needs machine components which are high quality, cost-efficient and light weight. The welding of different materials is a common technique to produce machine components capable of matching these goals, although some welding processes may negatively impact the quality of the components produced. Tailored Forming is a novel processing concept in which hybrid workpieces are fabricated by welding different metals together and subjecting them to deformation processing at elevated temperatures. The combination of plastic straining and high temperatures during forming leads to the activation of the recovery and recrystallization processes. These processes act to improve the mechanical properties of the component, by replacing the directional and coarse microstructure of the weld metal, with an equiaxed, fine microstructure after forging. The hybrid forging billets used in this study combine alloy steel (41Cr4) with plain carbon steel (C22.8), and are manufactured by laser beam welding. An experimental test matrix is employed, which utilises the variations of process parameters, to influence the geometry and microstructure of the materials' joining zone. The effects of the deformation processing of laser welded hybrid workpieces are characterised by destructive testing and metallography.