Hole-flanging behaviour of dual-phase steel using conventional and two-stage incremental forming processes

Abstract

ABSTRACT The present study aimed to analyse the hole-flanging behaviour of dual -phase steel using conventional and incremental forming processes. The sheet with different hole diameters (40, 30 and 20 mm) are prepared and tested. During conventional flanging operation, the effect of two different punch geometries (flat bottom and hemispherical) are used to study the hole-flanging ability. Whereas, in incremental forming operation, different tool paths are generated, i.e. single (90°) and two stage (45° + 90°). The results shows that the holes flanged using conventional process failed to flange the lower diameter hole which is attributed due to the higher tensile circumferential stresses acted along its circumference. Whereas, for hole flanged using incremental technique has shown similar observations except in case of two-stage strategy. The implementation two-stage strategy helps in successful formation of the flanges for lower diameter holes compared to the remaining one. Additionally, finite element simulations are performed to study various critical parameters such as strain path and thickness. The maximum value of strains and thickness reduction is found near the hole edge. The highest thinning (65%) is found in single-stage process and least (38.04%) in conventional flanging with hemispherical punch.