Mechanical behavior of HSLA350/440 and DP350/600 steels at different temperatures and strain rates

The present paper presents an experimental investigation of the mechanical behavior of HSLA350/440 and DP350/600 through uniaxial tensile tests, covering temperatures from 30 °C to 800 °C, and strain rates from 0.035 s⁻¹ to 1.35 s⁻¹ encompassing several conditions for the motor vehicle parts manufacturing process. Experimental data were analyzed and tensile flow curves were plotted. Yield strength (YS), ultimate tensile strength (UTS), and total elongation (EL) were determined. A severe reduction of formability was found at 600 °C for both materials. At 800 °C, the UTS was dramatically reduced to around 100 MPa for both materials. No benefit was detected for HSLA350/440 in hot working. On the other hand, the EL of DP350/600 had a straight increase at 800 °C according to the strain rate. The Hensel-Spittel coefficients were calibrated for experimental data to represent the materials in a finite element (FE) code in order to predict the springback. Experimental deep drawing operations were performed, and the results showed good agreement with the simulations. As a result, the calibrated Hensel-Spittel constitutive equation can predict the mechanical behavior of HSLA350/440 and DP350/600 through simulations in a wide range of temperatures and strain rates. (paper)