Recent Developments within Semi-Solid Forming at the Institute for Metal Forming Technology
This paper illustrates several research activities being carried out within the Center of Competence for Casting and Thixoforging Stuttgart (CCT `NOVUS´). A new method for manufacturing Metal Matrix Composites out of the semi-solid state has been developed at the Institute for Metal Forming Technology, Universitaet Stuttgart, and applied for patent pending. Within this new manufacturing method for the production of fibre and particle reinforced composites now disadvantages of liquid-phase-techniques can be reduced in combination with decreased manufacturing costs compared to conventional MMC-production technologies due to short cycle times and the ability of near-net-shape forming. It is obvious that manufacturing process in the fabrication of metal matrix composite materials will influence in some extent the performance of these materials. A current research project at the Institute for Metal Forming Technology (IFU), contributes implementing specific boundary condition of the manufacturing process to numerical analysis. Such boundary conditions exert direct influence on product quality. For manufacturing of metal matrix composites limiting factors are e.g. temperature, pressure, deformation, etc. Detecting input-parameter for numerical analysis basic rheological parameters, such as static and dynamic yield points, hysteresis and shear rate jump tests, detection of the differential structural parameter, evolution of apparent viscosity of different castalloys are topics of current research project at the Institue for Metal Forming Technology. For reheating-process of semi-solid alloys new technologies have been developed and applied for patent pending by the Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW). The two main advantages of this technique as compared with other induction heating techniques are the direct online determination of liquid-, solid fraction and heating-homogeneity as well as robustness against variations of prematerial (chemical composition, billet-diameter, etc.).
G. Hirt, A. Rassili, A. Bührig-Polaczek
M. Liewald and P. Unseld, "Recent Developments within Semi-Solid Forming at the Institute for Metal Forming Technology", Solid State Phenomena, Vols. 141-143, pp. 109-114, 2008