from the conferences organized by TANGER Ltd. provisional website
Regarding tool wear and energy consumption when forging steel parts, tailored preform geometries are beneficial. In particular, the number of forging steps can be reduced, in comparison to conventionally rolled cylindrical stock material, if preformed billets are used. In order to assess the potential offered by cast preforms as semi-finished products for a subsequent forging process, cylindrical steel billets (G42CrMo4) were cast by sand casting and then upset with different degrees of deformation φ (0.7-1.5), forging temperature (600-1200 °C) and ram speed (30-700 mm/s). Forging of conventional rolled bar material under the same forming conditions was used as a reference. After forming, the specimens were heat treated and the mechanical properties were determined by tensile tests (DIN EN ISO 6892-1) and notch impact tests (similar to DIN EN ISO 148-1). The microstructures were examined by metallographic analysis. For the investigated process variables, no significant influences on the tensile strengths or impact energies of the cast and forged specimens were found. While the tensile strengths of the cast and forged specimens meet the values of conventionally rolled and forged specimens, the impact energies of the cast and forged specimens surpass those of the reference. This is attributed to compressed pores, which were incompletely closed during forging. A criterion for the design of a die forging process of cast preforms will be derived based on the obtained results.Keywords: Hot forming, casting, steel, pore closure
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