The effect of rolling direction and strain rate on the tensile properties of DP450 and DP800 steels used in the automotive industry

Dual-phase steels are the most preferred steel group in the automotive industry. During their usage, rolling direction and strain rate of these steels with respect to rolling direction extremely important. In this study, the tensile test behaviors of DP450 and DP 800 dual phase steels were investigated depending on the strain rate and rolling direction. In the experimental studies the angles between rolling direction and tensile axis are 0°, 45°, 90° and strain rates are determined as 2.4x10-4, 2.4x10-3, 2.4x10-2 and 1.2x10-1 s-1. The results obtained in the study showed that the deformation rate of DP450 and DP800 steels had a greater effect on the tensile properties than the rolling direction effect. In both alloys, the values of yield and tensile strength increased with the increase in deformation rate, and the values of percent fracture elongation decreased substantially. In addition, the effect of strain rate on yield strength is greater than the effect of strain rate on tensile strength of both steels. In the DP800 steel the rate of increase in tensile strength with the deformation rate is lower than the DP450 steel, while the decrease rate of the elongation rate is higher. When the effect of the rolling direction is considered, both DP450 and DP800 steels have the highest yield and tensile strengths in the 45° rolling direction while both steels have lower elongation rates in the 45° rolling direction