Investigation into the Manufacture of Hybrid Wear Resistant Forging Tools using Tailored Forming Technology

  • Till, Michael (IFUM)

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Forging tools are subjected to a collective of high thermal, mechanical and chemical loads, which limit their tool life and thus the economic efficiency of the process. While forging, the tools are subjected to temperatures up to 800 °C, leading to a significant loss of strength in conventional hot-work tool steels. Additionally, cyclic temperature peaks coincide with the mechanical stress peaks at the end of the forming process. Nickel-based alloys, e.g. inconel, have high-temperature strength and tempering resistance, but are difficult to machine and much more expensive than conventional hot-work tool steels, making their use as monolithic material cost-ineffective. A resource- and cost-efficient way of achieving similar performance to a monolithic tool is offered by Tailored Forming technology, which allows a hybrid tool system to be manufactured from inconel. In addition, a microstructural texturing adapted to the forming process is induced in both materials, improving their strength and hardness. The objectives of the present work are the development and analysis of a process route for the production of inconel reinforced forming tools which exhibit a high resistance to thermo-mechanically induced failure patterns and lead to a significant increase in tool life. Within the scope of the work, hybrid tools are produced using Tailored Forming Technology. By forging pre-joined friction welded components, the surface enlargement was used to cover the hot work steel with a protective inconel layer. To this end, the process was designed numerically to adjust the material distribution according to the occurring loads. After forging, the tools were examined. The metallographic analyses and hardness measurements show a significant grain refinement and hardness increase in the inconel layer and a suitable hardening depth profile depending on forming temperatures. The results also show that no cracking occurs even when the inconel layer is severely thinned. In addition, fundamental findings on the formation of the joint zone were gained. The results show enormous potential for forging tool production with improved application properties in thermo-mechanically stressed areas.