Analyse des Einflusses des Ausgangsmaterials auf das erzielbare Mikrogefüge bei Alloy 718 Blechherstellung

The aim of the present work is to investigate the influence of the initial microstructure on the achievable microstructure during hot rolling of nickelbase-superalloy Alloy 718 (INCONEL718). Two materials, a forged slab with grain size ASTM 4-6, and a partial cogged slab, with grain size ASTM 4,5 8 and remaining casting structure up to 36%, were examined. The rolling process was simulated and analysed using the finite element program DEFORM™, for the simulation of microstructure, models from literature were used. For validation of simulated results, annealing tests at 950°C, 1000°C, 1015°C, 1020°C, 1050°C, 1100°C und 1150°C, as well as forming experiments with doublecones were performed. The deformation tests were conducted as multistep tests, with final deformation degrees of 0,3 and 0,4. The deformation rates were 2s-1, 1s-1, 0,1s-1, at temperatures of 980°C, 1000°C, 1030°C, 1050°C, und 1100°C. The samples were examined regarding recrystallised fraction and grain sizes. The results were used to identify possible process windows for the hot rolling process.