Parametric effects of single-point incremental forming on the hardness of high carbon steel sheets

Incremental sheet forming (ISF) is a promising die-less metal forming process where a rotating tool applies incremental pressure on the sheet to be deformed. However, a lack of available knowledge about the effect of process parameters on the produced part hinders the process from being widely used in the industry. One aspect to be considered is the effect of process parameters on the mechanical properties of the final product. For instance, hardness is a mechanical property that indicates the resistance of a material to elastoplastic deformation. This work investigates the effects of tool rotational speed, vertical step down, and feed rate on the hardness of high carbon steel (AISI 1075) sheet. A full-factorial experimental design for the three process parameters establishes a set of 27 experiments for a cone-forming process. Micro-hardness of the material is found to increase considerably from 185 to 252 HV due to strain hardening during the ISF process. Tool rotational speed and feed rate parameters have an insignificant effect on the hardness (p values of 0.829 and 0.538, respectively). Vertical step down of the tool is identified as the most influential parameter on hardness, with a p value of 0.001.