An experimental investigation on the ductility and post-form strength of a martensitic steel in a novel warm stamping process

In this study, a new lightweight forming technology, the fast-warm stamping technique, was proposed to form a martensitic steel (MS-W900Y1180 T) into a complex shaped component. The mechanical properties such as ductility and post-form strength (PFS) of the MS-W900Y1180 T (MS1180) steel were examined via uniaxial tensile tests at various temperatures (25–500 °C) and strain rates (0.01–5/s). Special attention has been paid to the effect of heating rate on thermo-mechanical properties and microstructure of the MS1180 steel with different heating rates. The results indicate that the ductility and post-form hardness of the MS1180 steel were improved by 25.7% and 5% respectively with increasing heating rate from 1 to 150 °C/s, which is attributed to the finer precipitated carbides and lower recovery at fast heating rate conditions. A U-shaped panel component was successfully formed using the proposed forming technology in a cycle time within 10 s. The fast-warm stamped components exhibited a post-form strength of 1140 MPa.