Author(s)

K. Watanabe, K. Natori, T. Tanaka & Y. Imaida

Abstract

The purpose of this study is to investigate the deformation property, under a high strain rate, of high strength steel sheets. The influence of strain rate on the Bauschinger effect is clarified, and the relation between the mechanical property and this influence is formulized. In this study, three kinds (590MPa, 780MPa, 980MPa) of high strength steel sheets of the Dual Phase type were applied. Both the rolling direction and the transverse direction specimens are created, and the compressive-tensile tests are conducted on three conditions of strain rate 7.0x10-3, 10 and 100/s. As a result, it is shown clearly in Dual Phase steels that the dependence of strain rate on the Bauschinger effect exists. In addition, with the transformation of material into high strength, it is demonstrated that consideration of the influence of the Bauschinger effect becomes increasingly important; however, the need for consideration of the dependence of the strain rate and the influence of strength anisotropy on the Bauschinger effect decrease for a material model in a numerical simulation. Keywords: sheet metal forming, mechanical property, compression test, tensile test, high speed deformation, dual phase steel, Bauschinger effect, strain rate dependence, strength anisotropy. 1 Introduction In recent years, in connection with the motion in the low carbon society towards earth’s environment protection, the improvement in fuel consumption of the automobile has been required strongly. Therefore, adopting high strength steel sheets as the composition material of the automobile body contributed to both the weight reduction of the body and the improvement in safety. It has been

Keywords

sheet metal forming, mechanical property, compression test, tensile test, high speed deformation, dual phase steel, Bauschinger effect, strain rate dependence, strength anisotrop