Influence of spindle speeds on the formability, microstructure, mechanical properties and fracture behaviour of Ti-6Al-4V alloy foils during single point micro incremental forming (SPMIF) process

Knowledge of the deformation behaviour of Ti-6Al-4V using single-point micro incremental forming (SPMIF) is very important to understand the physics behind the microstructural changes, and forming limit. In SPIF, shape changes in sheet metals up to ultra-thin sizes can be performed without using a die and punch (does not require any specific tooling as in the conventional forming process) and hence, this process is recommended for the fabrication of parts in the aerospace, automobile, and bio-medical industries. Furthermore, in SPIF, the components are manufactured using a hemispherical end tool moving along a predefined path with an enhanced forming limit. The present research work has focused on studying the formability, microstructure, mechanical properties and fracture mechanics of Ti–6Al–4V alloy foils during SPMIF. The importance of spindle speed on the forming limits of the Ti–6Al–4V alloy foil was studied and it was found that the maximum forming limits were achieved at higher spindle speeds (200 rpm) due to strengthening of basal texture and weakening of prismatic texture components. A forming limit strain (FLS) was drawn at different spindle speeds (100, 150, and 200 rpm). XRD, EBSD and TEM analyses were performed for the phase analysis, orientation and dislocation density respectively. The fracture behaviour was investigated and the void coalescence parameters were compared with respect to spindle speed.