High Strain Rate Deformation Behavior of Advanced High Strength Steels for Automotive Applications

The high strain rate deformation behavior of commercially available dual phase steel was studied by means of split Hopkinson bar apparatus in shear punch mode with an emphasis on the influence of microstructure. The cold rolled sheet material was subjected to a variety of heat treatment conditions to produce several different microstructures. Dual phase microstructures with different fractions of martensite were obtained by changing intercritical annealing temperature and time. Various microstructures of ferrite plus pearlite, or acicular ferrite/bainite, or bainite and martensite/carbide were obtained by changing the cooling rate after annealing. The effects of low temperature tempering and bake hardening treatment were also investigated for some selected specimens.