Abstract
This study investigates the effect of tool diameter and forming temperature on the microstructural evolution and formability of AA6061-T6 aluminium alloy in Heat Assisted Incremental Sheet Forming (HAISF). Three tool diameters (6 mm, 8 mm, and 10 mm) and three temperature levels (room temperature, \(150^{\,\circ }\) C, and \(300^{\,\circ }\) C) were considered, while other process parameters—including step depth (0.4 mm), spindle speed (1250 RPM), and feed rate (600 mm/min)—were held constant. A conical frustum geometry with a \(60^{\circ }\) wall angle and target forming depth of 30 mm was used to assess the deformation response. Microstructural evaluation via SEM and EDS revealed distinct particle fragmentation, shear band formation, and oxide development depending on the forming temperatures under various tool diameters. While the 6 mm tool enabled full-depth forming under all temperatures, the 10 mm tool led to premature failure due to matrix degradation and \(Mg_2Si\) particle loss, especially at elevated temperatures. Fracture depth, microhardness, surface roughness, sheet thinning, and geometrical accuracy were systematically analysed, showing that the 8 mm tool at \(150^{\,\circ }\) C provided a favourable balance between formability and structural integrity. The findings highlight the critical interplay between tool size and thermal input in tailoring the ISF process for high-strength aluminium alloys.
Graphic Abstract
