Dynamic Behaviour of Pre-Strained and Baked Steels Using Split Hopkinson Pressure Bar (SHPB)

A Split Hopkinson Pressure Bar (SHPB) was used to obtain dynamic behaviour of various steels at large strains and high strain rate. The dynamic loading response was compared between mild steels and cold rolled high strength steels, Dual Phase 590 and TRIP 780. Only sheet samples were available for the high strength steels, and thus confirmation tests were carried out on mild steel to determine whether behaviour of sandwiched samples were equivalent to normal bulk samples. The effect of pre-straining and bake hardening on dynamic behaviour of sheet metals was then investigated. Preliminary results show a difference between the bake hardening effect on pre-strained Dual Phase and TRIP steels. Bake hardening increased the mass specific energy absorption for the pre-strained Dual phase sample, whereas the pre-strained TRIP sample mass energy absorption decreased. Further work is necessary to verify this difference and understand the material behaviours.