Abstract
Incremental sheet metal forming is known for its high flexibility, making it suitable for fabricating low-batch, highly customized complex parts. In this paper, a localized multi-pass toolpath referred to as localized reforming, with reverse forming in a region of interest, is employed within the DSIF process to manipulate the mechanical properties of a truncated pyramid formed from austenitic stainless steel sheet, SS304, through deformation-induced martensite transformation. The toolpath effect in localized reforming is examined in terms of martensite transformation, geometrical accuracy, and thickness distribution. The results are compared with a conventional toolpath, i.e., forming in a single pass. Findings reveal that varying toolpath yields different levels of martensite transformation, while the final geometry and thickness distribution remain fairly similar using the two toolpaths. The study demonstrates that localized reforming significantly increases martensite transformation in the specified region, i.e., the center of the pyramid wall, to ∼70%, with a martensite fraction remaining around 25% elsewhere. In comparison, using a single pass forming toolpath leads to a decreasing martensite fraction from the base of the pyramid towards the apex, due to the heat generated, with the value <10% all along the wall. Through finite element simulation, it is shown that the increase in martensite transformation of the region of interest is with the plastic deformation accumulation during the reverse pass. The significance of these findings lies in the ability to manipulate the mechanical properties in specific regions by employing a reforming toolpath in the DSIF process.
