No abstract

The process of thixoforming, which has been part of many researches during the last decades, combines the advantages of forging and casting for the shaping of metallic components. But due to the high temperatures of semi-solid steel alloys high demands on the tools are requested. To resists the thermal and mechanical loads (wear, friction, thermal and thermomechanical fatigue) protecting thin films are necessary. In this regard crystalline gamma-Al2O3 deposited via Physical Vapour Deposition (PVD) is a promising candidate: It exhibits high thermal stability, high oxidation resistance and high hot hardness. In the present work the application of a (Ti, Al)N/gamma-Al2O3 coating deposited by means of Magnetron Sputter Ion Plating in an industrial coating unit is presented. The coating was analysed by means of Rockwell test, nanoindentation, and Scanning Electron Microscopy (SEM). The coated tool was tested in thixoforging experiments with steel grade X210CrW12 (AlSI D6). The surface of the coated dies was examined with Scanning Electron Microscope (SEM) after 22, 42, 90 and 170 forging cycles.

No abstract

Semi-solid forming of steels has the potential to produce components with good mechanical properties and complicated geometry from high strength steels due to the advantages of forging and casting processes combination. Due to the high process temperatures thixoforging of steels has to meet high demands on process parameters accuracy and control. The thixoforging process parameters like billet temperature, temperature distribution after the reheating, Argon gas pressure, transportation time and forging load were experimentally investigated on thixoforging of a non axis-symmetric 4 kg demonstrator part of steel grade X210CrW12. Due to the high process temperatures, thermal and mechanical loads the development of a suitable tool concept is necessary. Hardened hot working steel X38CrMoV5-1 as a tool bulk material with protecting thin film crystalline (Ti,Al)N/γ-Al 2 O 3 deposited by means of Physical Vapour Deposition (PVD) showed good results in first experimental series. The Scanning Electron Microscope images show mechanical damage of the tool radii edge while the rest tool surface look intact after 170 thixoforging cycles.