Laser assisted conical spin forming of dual phase automotive steel. Experimental demonstration of work hardening reduction and forming limit extension

Abstract

Laser Assisted Spin Forming is investigated for improving the poor formability of Advanced High Strength Steel\ud DP-800 and Aeronautic Grade Titanium alloy, with minor or no change in microstructure, final properties improvements and no damage to coating, thanks to controlled energy input and fast thermal cycles. IR imaging and\ud force-torque monitoring are used to characterise the forming process. Residual stress measurement, microstructure,\ud microhardness and EBSD are used to study the formed parts under the combined action of laser and mechanical force. A micromechanism of laser assisted spinning is proposed, as well as advantages and limitations of the\ud technique.Peer ReviewedPostprint (published version

The classification and a review of hot power spinning of difficult-to-deform metals

“…The results show that the deformation degree of X5CrNi18-10 stainless steel is increased by 15-25%, while the strain hardening of TiAl6V4 titanium alloy is decreased by 40% and the maximum forming force is decreased by 20%. Romero et al (2010) investigated the shear spinning for conical parts and the flow forming for tubular parts of dual-phase high strength steel DP600, DP780 and DP800 by laser heating (Figure 4). The results show that the influence of high temperature oxidation on microstructure of unformed area can be avoided effectively because only the forming zone which contacts with the roller is heated, and the forming force is decreased by 20%.…”

“…Compared with the flame-assisted hot power spinning, the heating temperature can be controlled precisely during laser-assisted hot power spinning. But due to the small heating zone caused by the small laser beam and the discontinuous heating of the forming zone during the laser-assisted hot power spinning, the processing parameters, such as the heating temperature, the reduction of blank thickness and the feed rate of roller, and the power parameters of laser, such as the focal distance, angle and spot position of the laser beam, must be strictly controlled to ensure the uniformly material flow (Romero et al, 2010). Figure 4(c) shows the crack caused by the unmatched processing parameters and the laser parameters during laser-assisted hot shear spinning (Romero et al, 2010).…”

“…Klocke and Wehrmeister (2003) reported that the forming limit of stainless steel X5CrNi18-10 increases by 15%-25% and the strain hardening decreases by 40% through hot shear spinning. Romero et al (2010) reported that the residual stress of the spun parts of DP steels (dual-phase high strength steels) decreases by 30%-40% through hot shear spinning. Murata et al (2005) found that during hot flow forming of the magnesium alloy tubes, the Vickers hardness decreases with the increasing of the spinning temperature, the forming limit improves greatly when the heating temperature is above the recrystallisation one.…”

Laser-assisted metal spinning for an efficient and flexible processing of challenging materials

“…published in [8] or a provisional experimental set-up published by [9] facilitated to proof the general feasibility and the advantages of laser-assisted shear forming and multi-pass spinning operations but suffered several limitations. Especially with regard to multi-pass spinning limited flexibility and high programming efforts have been deficits.…”

Hydroforming of locally heat treated tubes

“…As a consequence, in order to maintain the desired thermal gradients in the workpiece, complex differential heating/cooling strategies of punches, moulds and other tools are often required [17]. Even when the heat conduction problems due to a complete contact to a die or mould are negligible, the forming workpiece must be very accessible from at least one of its sides, such as in conical spinning [18] or in free bulge hydroforming [19]. This is because the most rapid and effective heating techniques (laser beam and induction) require close but contactless interaction with the interested region of the workpiece.…”