The Optimization Of Stamping Performance For High Strength Steel DP590

With the rapid development of auto industry, high strength steel has gradually developed into a strong competitive new material for achieving the requirements of lightweight, and the DP dual phase steel as a kind of high strength steel is an important part of structural material in automotive. In order to widely apply the materials in various fields, the forming process for high strength steel and its development is an important direction in the field of materials processing in the future.First of all, the tensile properties for DP590 dual phase steel under different temperature were tested; true stress strain curves are obtained under different temperature, those data provide reliable experimental parameters for subsequent numerical simulation. The cold deep drawing experiments for DP590 sheet of 0.8 mm thickness were simulated by using dynaform software under different conditions. The simulation results show that the deep drawing limit for the DP590 sheet metal size is 46 mm. With stamping speed increase, the ratio of the sheet reduction increase until it burst. Along with the blank-holder force increase, the wrinkling trend of sheet metal decreases greatly, but the reduction ratio increases, its fracture trend increases. On the basis of the stress strain curve of sheet metal under different temperature, the deep drawing process was simulated under different temperature, the simulation results show that the equivalent stress of sheet metal drop with the temperature increases, and the forming performance improvement.On the basis of numerical simulation, the deep drawing of the B340/590 DP sheet metal of 0.8 mm thickness were tested, the test results show that the deep drawing limit ratio of the B340/590 DP sheet metal with 0.8 mm thickness is 0.52 and decreasing the stamping speed will improve the properties of the sheet metal forming. According to the characteristics of the deep drawing process and the controllability of the servo press, the variation of the stamping speed mode will improve the formability of sheet metal and reduce the forming defects such as cracking wrinkling in the process of experiment. By controlling the blank holder force accurately in the stamping test system, the deep drawing experiments of 46 mm diameter sheet were tested under different blank holder force, the experimental results show that when the blank-holder force is set to 5kN, the wrinkling of the sheet is obvious which is in line with the previous simulation results. Deep drawing test has been carried out under different temperature for the sheet metal with 48 mm diameter, the experimental results show that when the sample heated to 300℃, the formability of sheet metal decreased compared with the normal temperature due to the blue brittle phenomenon; when heated to the temperature above 400℃, sheet metal the deep drawing limit for sheet metals increase to size 48 mm from 46 mm at room temperature, and under the condition of heating, the thickness distribution become more uniform in deep drawing test specimen, and the formability is better, which is consistent with the previous simulation results.The bulge ability of dual-phase high strength steel DP590 has been studied in sheet testing system of servo presses. The stamping punch position and velocity and load were recorded by using the precision sensors in the testing system. The IE values of DP590 with 0.8mm thickness were obtained at different punching speeds, lubrication condition and blank-holder force. The experimental results show that the bulge ability of DP590 steel was obviously affected by the stamping speed, lubrication condition and blank-holder force, and the research is helpful to the lightweight application and the optimization of process parameters.