The Tailored Forming process chain is used to manufacture hybrid components and consists of a joining process or Additive Manufacturing for various materials (e.g. deposition welding), subsequent hot forming, machining and heat treatment. In this way, components can be produced with materials adapted to the load case. For this paper, hybrid shafts are produced by deposition welding of a cladding made of X45CrSi9-3 onto a workpiece made from 20MnCr5. The hybrid shafts are then formed by means of cross-wedge rolling. It is investigated, how the thickness of the cladding and the type of cooling after hot forming (in air or in water) affect the properties of the cladding. The hybrid shafts are formed without layer separation. However, slight core loosening occurres in the area of the bearing seat due to the Mannesmann effect. The microhardness of the cladding is only slightly effected by the cooling strategy, while the microhardness of the base material is significantly higher in water cooled shafts. The microstructure of the cladding after both cooling strategies consists mainly of martensite. In the base material, air cooling results in a mainly ferritic microstructure with grains of ferrite-pearlite. Quenching in water results in a microstructure containing mainly martensite.

The Collaborative Research Center 1153 is investigating an innovative process chain for the production of hybrid components. The hybrid workpieces are first joined and then formed by cross-wedge rolling. Pinion shafts were manufactured to investigate the behavior of the joining zone under increased complexity of the forming process. For this purpose, six types of workpieces produced by three types of joining processes were formed into pinion shafts. The reference process provides a shaft with a smooth bearing seat. It was found that the increased complexity did not present any challenges compared to the reference processes. A near-net shape geometry was achieved for the pinions made of steel.

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Forgings are produced in several process steps, the so-called forging sequence. The design of efficient forging sequences is a very complex and iterative development process. In order to automate this process and to reduce the development time, a method is presented here, which automatically generates multi-stage forging sequences for different forging geometries on the basis of the component geometry (STL file). The method was developed for closed die forging. The individual modules of this forging sequence design method (FSD method) as well as the functioning of the algorithm for the generation of the intermediate forms are presented. The method is applied to different forgings with different geometrical characteristics. The generated forging sequences are checked with FE simulations for the quality criteria form filling and freedom from folds. The simulation results show that the developed FSD method provides good approximate solutions for an initial design of forging sequences for closed die forging in a short time.

Tailored forming is used to produce hybrid components in which the materials used are locally adapted to the different types of physical, chemical and tribological requirements. In this paper, a Tailored Forming process chain for the production of a hybrid shaft with a bearing seat is investigated. The process chain consists of the manufacturing steps laser hot-wire cladding, cross-wedge rolling, turning and deep rolling. A cylindrical bar made of mild steel C22.8 is used as the base material, and a cladding of the martensitic valve steel X45CrSi9-3 is applied in the area of the bearing seat to achieve the strength and hardness required. It is investigated how the surface and subsurface properties of the hybrid component, such as hardness, microstructure and residual stress state, change within the process chain. The results are compared with a previous study in which the austenitic stainless steel X2CrNiMo19-12 was investigated as a cladding material. It is shown that the residual stress state after hot forming depends on the thermal expansion coefficients of the cladding material.