Investigating the incremental forming capabilities of extra deep drawn steel

Abstract

Incremental Sheet Forming (ISF) is a sheet metal forming process, which relies on minimum part-specific tooling. Extra Deep Drawn (EDD) steel has been used for making door inners, dash panels, bodyside inners, etc. due to its good weldability and relatively low yield strength. However, to date very limited work is reported on ISF of EDD steel. Besides, no work, which exhaustively discusses the practicability of EDD steel for effectual incremental forming of components, is found to be reported. The present work discusses the ISF of EDD steel sheets and examines the limitations of ISF in forming the parts out of 1.0 mm thick EDD steel sheets. Two geometries, i.e., ellipsoidal cone (with varying wall angle) and truncated cone (with constant wall angle) were used as test cases to evaluate the formability of EDD steel sheets, in terms of Critical Wall Angle (CWA). Further, the formability of EDD steel with ISF is evaluated using both strain-based and stress-based forming limit curves. The thickness distribution, geometrical accuracy, forming forces, and surface roughness and hardness are evaluated in the formed components. The work, through numerical simulations and experimental analyses, investigates the process capabilities of ISF to form the EDD steel sheets in terms of formability, thickness distribution, geometrical accuracy, forming forces, and surface roughness and hardness to ascertain the scope of the proposed process.

Surface roughness of AISI 1010 and AISI 304 of PEMFC bipolar plates with microscale hydroformed capillary channels

“…For the stainless-steel samples, the roughness continued to increase as forming pressure increases up to about 25 MPa. Mild steel samples show linear relationship up to about 17 MPa, then it appears constant or slightly decreases until fracture.The linear relationship observed in the roughness seen in Figure10for the stainless steel bulge test samples is consistent with results from previous studies 16,26. The slight dip experienced at higher strains, near the burst pressure has also been reported by other researchers 27.…”

“…The linear relationship observed in the roughness seen in Figure 10 for the stainless steel bulge test samples is consistent with results from previous studies. 16,26 The slight dip experienced at higher strains, near the burst pressure has also been reported by other researchers. 27 This slight shift from linearity can be attributed to deformation induced thinning at the pole of the bulged dome, where the roughness was measured and which experienced the highest strains in the sample.…”